Update references in README

.gitattributes

@@ -0,0 +1,6 @@
+#
+# https://help.github.com/articles/dealing-with-line-endings/
+#
+# These are explicitly windows files and should use crlf
+*.bat           text eol=crlf
+

.gitignore

@@ -1,3 +1,8 @@
 /*.iml
 /.idea
 /out
+# Ignore Gradle project-specific cache directory
+.gradle
+
+# Ignore Gradle build output directory
+build

README.md

@@ -14,7 +14,7 @@ Dann einfach alle TODOs abarbeiten.
 ## Sequenzen
 
 Für jede Datenstruktur, die Sequenzen darstellen,
-sollte das Interface [`SequenceProcessor`](src/aud/exam/prep/SequenceProcessor.java)
+sollte das Interface [`SequenceProcessor`](src/main/java/aud/exam/prep/SequenceProcessor.java)
 einmal iterativ und einmal rekursiv implementiert werden.
 
 Jede fast Methode in `SequenceProcessor` stellt eine Aufgabe dar,
@@ -38,4 +38,4 @@ durch eine Sequenz `s`.
 <https://docs.oracle.com/javase/8/docs/api/java/util/Objects.html#equals-java.lang.Object-java.lang.Object->
 
 1. Neues Array vom Typ `T` erstellen:
-[`Arrays.newArray(size)`](src/aud/exam/prep/array/Arrays.java)
+[`Arrays.newArray(size)`](src/main/java/aud/exam/prep/array/Arrays.java)

build.gradle.kts

@@ -0,0 +1,32 @@
+/*
+ * This file was generated by the Gradle 'init' task.
+ *
+ * This generated file contains a sample Java application project to get you started.
+ * For more details take a look at the 'Building Java & JVM projects' chapter in the Gradle
+ * User Manual available at https://docs.gradle.org/7.4.1/userguide/building_java_projects.html
+ */
+
+plugins {
+    // Apply the application plugin to add support for building a CLI application in Java.
+    application
+}
+
+repositories {
+    // Use Maven Central for resolving dependencies.
+    mavenCentral()
+}
+
+dependencies {
+    // Use JUnit Jupiter for testing.
+    testImplementation("org.junit.jupiter:junit-jupiter:5.8.1")
+}
+
+application {
+    // Define the main class for the application.
+    mainClass.set("aud.exam.prep.Main")
+}
+
+tasks.named<Test>("test") {
+    // Use JUnit Platform for unit tests.
+    useJUnitPlatform()
+}

gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.4.1-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

gradlew

@@ -0,0 +1,234 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
+
+APP_NAME="Gradle"
+APP_BASE_NAME=${0##*/}
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+# Collect all arguments for the java command;
+#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+#     shell script including quotes and variable substitutions, so put them in
+#     double quotes to make sure that they get re-expanded; and
+#   * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"

gradlew.bat

@@ -0,0 +1,89 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

settings.gradle.kts

@@ -0,0 +1,10 @@
+/*
+ * This file was generated by the Gradle 'init' task.
+ *
+ * The settings file is used to specify which projects to include in your build.
+ *
+ * Detailed information about configuring a multi-project build in Gradle can be found
+ * in the user manual at https://docs.gradle.org/7.4.1/userguide/multi_project_builds.html
+ */
+
+rootProject.name = "aud-exam-prep"

src/aud/exam/prep/list/DoubleListItem.java

@@ -1,7 +0,0 @@
-package aud.exam.prep.list;
-
-public class DoubleListItem<T> {
-    public T key;
-    public DoubleListItem<T> next;
-    public DoubleListItem<T> prev;
-}

src/aud/exam/prep/list/SingleListItem.java

@@ -1,6 +0,0 @@
-package aud.exam.prep.list;
-
-public class SingleListItem<T> {
-    public T key;
-    public SingleListItem<T> next;
-}

src/aud/exam/prep/tree/OrderedBinaryTreeNodeProcessor.java

@@ -1,36 +0,0 @@
-package aud.exam.prep.tree;
-
-abstract class OrderedBinaryTreeNodeProcessor<V> implements OrderedTreeProcessor<V, BinaryTreeNode<V>> {
-    @Override
-    public BinaryTreeNode<V> newEmptyTree() {
-        return null;
-    }
-
-    @Override
-    public Iterable<V> iterate(BinaryTreeNode<V> tree) {
-        return () ->
-                new BinaryTreeIterator<>(tree);
-    }
-
-    @Override
-    public void print(BinaryTreeNode<V> tree) {
-        printRec(tree, 0);
-    }
-
-    private void printRec(BinaryTreeNode<V> tree, int indent) {
-        if (tree == null) {
-            System.out.println("- *");
-            return;
-        }
-
-        System.out.println("-> " + tree.key);
-
-        System.out.print(" |".repeat(indent));
-        System.out.print(" L");
-        printRec(tree.left, indent + 1);
-
-        System.out.print(" |".repeat(indent));
-        System.out.print(" L");
-        printRec(tree.right, indent + 1);
-    }
-}

src/main/java/aud/exam/prep/Main.java

@@ -0,0 +1,11 @@
+/*
+ * This Java source file was generated by the Gradle 'init' task.
+ */
+package aud.exam.prep;
+
+public class Main {
+
+    public static void main(String[] args) {
+        System.out.println("Hello World!");
+    }
+}

src/main/java/aud/exam/prep/list/DoubleListItem.java

@@ -0,0 +1,17 @@
+package aud.exam.prep.list;
+
+public class DoubleListItem<T> implements ListItem<T> {
+    public T key;
+    public DoubleListItem<T> prev;
+    public DoubleListItem<T> next;
+
+    @Override
+    public T head() {
+        return key;
+    }
+
+    @Override
+    public ListItem<T> tail() {
+        return next;
+    }
+}

src/main/java/aud/exam/prep/list/DoubleListItemProcessor.java

@@ -0,0 +1,12 @@
+package aud.exam.prep.list;
+
+import aud.exam.prep.SequenceProcessor;
+
+abstract class DoubleListItemProcessor<T> implements SequenceProcessor<T, DoubleListItem<T>> {
+
+    @Override
+    public Iterable<T> iterate(DoubleListItem<T> list) {
+        return () ->
+            new ListItemIterator<>(list);
+    }
+}

src/main/java/aud/exam/prep/list/IterativeDoubleListItemProcessor.java

@@ -0,0 +1,194 @@
+package aud.exam.prep.list;
+
+import aud.exam.prep.Pair;
+
+import java.util.Comparator;
+
+public class IterativeDoubleListItemProcessor<T> extends DoubleListItemProcessor<T> {
+
+    @Override
+    public boolean find(DoubleListItem<T> list, T t) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean findBinary(DoubleListItem<T> list, T t, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean override(DoubleListItem<T> list, T from, T to) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean overrideAll(DoubleListItem<T> list, T from, T to) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean overrideAt(DoubleListItem<T> list, T to, int index) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void insertInOrder(DoubleListItem<T> list, T t, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean remove(DoubleListItem<T> list, T t) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean removeAll(DoubleListItem<T> list, T t) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean isAscending(DoubleListItem<T> list, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public T max(DoubleListItem<T> list, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public T secondMax(DoubleListItem<T> list, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean isItemWiseLessOrEqual(DoubleListItem<T> a, DoubleListItem<T> b, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean isItemWiseLess(DoubleListItem<T> a, DoubleListItem<T> b, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean isLexSmaller(DoubleListItem<T> a, DoubleListItem<T> b, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void exchangePairs(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void rotateTriples(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void removeEverySecond(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void doubleAllKeys(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public DoubleListItem<T> rotateRight(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public DoubleListItem<T> rotateLeft(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void removeDuplicates(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public DoubleListItem<T> invert(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public DoubleListItem<T> clone(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public DoubleListItem<T> alternate(DoubleListItem<T> a, DoubleListItem<T> b) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public DoubleListItem<T> merge(DoubleListItem<T> a, DoubleListItem<T> b, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public Pair<DoubleListItem<T>, DoubleListItem<T>> divideAlternating(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public Pair<DoubleListItem<T>, DoubleListItem<T>> divideAlternatingByRuns(DoubleListItem<T> list, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public Pair<DoubleListItem<T>, DoubleListItem<T>> divideByPivot(DoubleListItem<T> list, T pivot, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean check(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public DoubleListItem<T> create(Iterable<T> iterable) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public Iterable<T> iterate(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+}

src/main/java/aud/exam/prep/list/IterativeSingleListItemProcessor.java

@@ -0,0 +1,194 @@
+package aud.exam.prep.list;
+
+import aud.exam.prep.Pair;
+
+import java.util.Comparator;
+
+public class IterativeSingleListItemProcessor<T> extends SingleListItemProcessor<T> {
+
+    @Override
+    public boolean find(SingleListItem<T> list, T t) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean findBinary(SingleListItem<T> list, T t, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean override(SingleListItem<T> list, T from, T to) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean overrideAll(SingleListItem<T> list, T from, T to) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean overrideAt(SingleListItem<T> list, T to, int index) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void insertInOrder(SingleListItem<T> list, T t, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean remove(SingleListItem<T> list, T t) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean removeAll(SingleListItem<T> list, T t) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean isAscending(SingleListItem<T> list, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public T max(SingleListItem<T> list, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public T secondMax(SingleListItem<T> list, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean isItemWiseLessOrEqual(SingleListItem<T> a, SingleListItem<T> b, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean isItemWiseLess(SingleListItem<T> a, SingleListItem<T> b, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean isLexSmaller(SingleListItem<T> a, SingleListItem<T> b, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void exchangePairs(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void rotateTriples(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void removeEverySecond(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void doubleAllKeys(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public SingleListItem<T> rotateRight(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public SingleListItem<T> rotateLeft(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void removeDuplicates(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public SingleListItem<T> invert(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public SingleListItem<T> clone(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public SingleListItem<T> alternate(SingleListItem<T> a, SingleListItem<T> b) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public SingleListItem<T> merge(SingleListItem<T> a, SingleListItem<T> b, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public Pair<SingleListItem<T>, SingleListItem<T>> divideAlternating(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public Pair<SingleListItem<T>, SingleListItem<T>> divideAlternatingByRuns(SingleListItem<T> list, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public Pair<SingleListItem<T>, SingleListItem<T>> divideByPivot(SingleListItem<T> list, T pivot, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean check(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public SingleListItem<T> create(Iterable<T> iterable) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public Iterable<T> iterate(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+}

src/main/java/aud/exam/prep/list/ListItem.java

@@ -0,0 +1,8 @@
+package aud.exam.prep.list;
+
+public interface ListItem<T> {
+
+    T head();
+
+    ListItem<T> tail();
+}

src/main/java/aud/exam/prep/list/ListItemIterator.java

@@ -0,0 +1,24 @@
+package aud.exam.prep.list;
+
+import java.util.Iterator;
+
+public class ListItemIterator<T> implements Iterator<T> {
+
+    private ListItem<T> current;
+
+    public ListItemIterator(ListItem<T> current) {
+        this.current = current;
+    }
+
+    @Override
+    public boolean hasNext() {
+        return current != null;
+    }
+
+    @Override
+    public T next() {
+        T t = current.head();
+        current = current.tail();
+        return t;
+    }
+}

src/main/java/aud/exam/prep/list/RecursiveDoubleListItemProcessor.java

@@ -0,0 +1,253 @@
+package aud.exam.prep.list;
+
+import aud.exam.prep.Pair;
+
+import java.util.Comparator;
+import java.util.HashSet;
+import java.util.Iterator;
+
+public class RecursiveDoubleListItemProcessor<T> extends DoubleListItemProcessor<T> {
+
+    @Override
+    public boolean find(DoubleListItem<T> list, T t) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean findBinary(DoubleListItem<T> list, T t, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean override(DoubleListItem<T> list, T from, T to) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean overrideAll(DoubleListItem<T> list, T from, T to) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean overrideAt(DoubleListItem<T> list, T to, int index) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void insertInOrder(DoubleListItem<T> list, T t, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean remove(DoubleListItem<T> list, T t) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean removeAll(DoubleListItem<T> list, T t) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean isAscending(DoubleListItem<T> list, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public T max(DoubleListItem<T> list, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public T secondMax(DoubleListItem<T> list, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean isItemWiseLessOrEqual(DoubleListItem<T> a, DoubleListItem<T> b, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean isItemWiseLess(DoubleListItem<T> a, DoubleListItem<T> b, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean isLexSmaller(DoubleListItem<T> a, DoubleListItem<T> b, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void exchangePairs(DoubleListItem<T> list) {
+        if (list == null || list.next == null || list.next.next == null) {
+            return;
+        }
+
+        var next = list.next;
+        var nextNext = next.next;
+        var rest = nextNext.next;
+
+        list.next = nextNext;
+        nextNext.prev = list;
+
+        nextNext.next = next;
+        next.prev = nextNext;
+
+        next.next = rest;
+        if (rest != null) {
+            rest.prev = next;
+        }
+
+        exchangePairs(list.next.next);
+    }
+
+    @Override
+    public void rotateTriples(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void removeEverySecond(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void doubleAllKeys(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public DoubleListItem<T> rotateRight(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public DoubleListItem<T> rotateLeft(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void removeDuplicates(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public DoubleListItem<T> invert(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public DoubleListItem<T> clone(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public DoubleListItem<T> alternate(DoubleListItem<T> a, DoubleListItem<T> b) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public DoubleListItem<T> merge(DoubleListItem<T> a, DoubleListItem<T> b, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public Pair<DoubleListItem<T>, DoubleListItem<T>> divideAlternating(DoubleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public Pair<DoubleListItem<T>, DoubleListItem<T>> divideAlternatingByRuns(DoubleListItem<T> list, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public Pair<DoubleListItem<T>, DoubleListItem<T>> divideByPivot(DoubleListItem<T> list, T pivot, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean check(DoubleListItem<T> list) {
+        return checkRec(list, new HashSet<>(), null);
+    }
+
+    private boolean checkRec(DoubleListItem<T> list, HashSet<DoubleListItem<T>> seen, DoubleListItem<T> prev) {
+        if (list == null) {
+            if (seen.isEmpty()) {
+                return true;
+            }
+
+            if (prev == null) {
+                return true;
+            }
+
+            return prev.next == null;
+        }
+
+        if (list.prev != prev) {
+            return false;
+        }
+
+        if (prev != null && prev.next != list) {
+            return false;
+        }
+
+        if (list.key == null) {
+            return false;
+        }
+
+        if (seen.contains(list)) {
+            return false;
+        }
+
+        seen.add(list);
+        return checkRec(list.next, seen, list);
+    }
+
+    @Override
+    public DoubleListItem<T> create(Iterable<T> iterable) {
+        var iter = iterable.iterator();
+        return createRec(iter, null);
+    }
+
+    private DoubleListItem<T> createRec(Iterator<T> iter, DoubleListItem<T> prev) {
+        if (!iter.hasNext()) {
+            return null;
+        }
+
+        var item = new DoubleListItem<T>();
+        item.key = iter.next();
+        item.next = createRec(iter, item);
+        item.prev = prev;
+
+        return item;
+    }
+}

src/main/java/aud/exam/prep/list/RecursiveSingleListItemProcessor.java

@@ -0,0 +1,194 @@
+package aud.exam.prep.list;
+
+import aud.exam.prep.Pair;
+
+import java.util.Comparator;
+
+public class RecursiveSingleListItemProcessor<T> extends SingleListItemProcessor<T> {
+
+    @Override
+    public boolean find(SingleListItem<T> list, T t) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean findBinary(SingleListItem<T> list, T t, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean override(SingleListItem<T> list, T from, T to) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean overrideAll(SingleListItem<T> list, T from, T to) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean overrideAt(SingleListItem<T> list, T to, int index) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void insertInOrder(SingleListItem<T> list, T t, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean remove(SingleListItem<T> list, T t) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean removeAll(SingleListItem<T> list, T t) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean isAscending(SingleListItem<T> list, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public T max(SingleListItem<T> list, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public T secondMax(SingleListItem<T> list, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean isItemWiseLessOrEqual(SingleListItem<T> a, SingleListItem<T> b, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean isItemWiseLess(SingleListItem<T> a, SingleListItem<T> b, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean isLexSmaller(SingleListItem<T> a, SingleListItem<T> b, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void exchangePairs(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void rotateTriples(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void removeEverySecond(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void doubleAllKeys(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public SingleListItem<T> rotateRight(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public SingleListItem<T> rotateLeft(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public void removeDuplicates(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public SingleListItem<T> invert(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public SingleListItem<T> clone(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public SingleListItem<T> alternate(SingleListItem<T> a, SingleListItem<T> b) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public SingleListItem<T> merge(SingleListItem<T> a, SingleListItem<T> b, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public Pair<SingleListItem<T>, SingleListItem<T>> divideAlternating(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public Pair<SingleListItem<T>, SingleListItem<T>> divideAlternatingByRuns(SingleListItem<T> list, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public Pair<SingleListItem<T>, SingleListItem<T>> divideByPivot(SingleListItem<T> list, T pivot, Comparator<T> cmp) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public boolean check(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public SingleListItem<T> create(Iterable<T> iterable) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+
+    @Override
+    public Iterable<T> iterate(SingleListItem<T> list) {
+        // TODO: Your training
+        throw new RuntimeException("unimplemented");
+    }
+}

src/main/java/aud/exam/prep/list/SingleListItem.java

@@ -0,0 +1,17 @@
+package aud.exam.prep.list;
+
+public class SingleListItem<T> implements ListItem<T> {
+
+    public T key;
+    public SingleListItem<T> next;
+
+    @Override
+    public T head() {
+        return key;
+    }
+
+    @Override
+    public ListItem<T> tail() {
+        return next;
+    }
+}

src/main/java/aud/exam/prep/list/SingleListItemProcessor.java

@@ -0,0 +1,6 @@
+package aud.exam.prep.list;
+
+import aud.exam.prep.SequenceProcessor;
+
+abstract class SingleListItemProcessor<T> implements SequenceProcessor<T, SingleListItem<T>> {
+}

src/main/java/aud/exam/prep/tree/OrderedBinaryTreeNodeProcessor.java

@@ -0,0 +1,15 @@
+package aud.exam.prep.tree;
+
+abstract class OrderedBinaryTreeNodeProcessor<V> implements OrderedTreeProcessor<V, BinaryTreeNode<V>> {
+
+    @Override
+    public BinaryTreeNode<V> newEmptyTree() {
+        return null;
+    }
+
+    @Override
+    public Iterable<V> iterate(BinaryTreeNode<V> tree) {
+        return () ->
+            new BinaryTreeIterator<>(tree);
+    }
+}

src/main/java/aud/exam/prep/tree/OrderedTreeProcessor.java

@@ -3,6 +3,7 @@ package aud.exam.prep.tree;
 import aud.exam.prep.Pointer;
 
 import java.util.Comparator;
+import java.util.function.Predicate;
 
 /**
  * Instances of this interface can work with any "valid" tree of type <code>T</code>.
@@ -27,6 +28,8 @@ public interface OrderedTreeProcessor<V, T> {
 
     boolean removeAll(Pointer<T> t, V v, Comparator<V> cmp);
 
+    T removeIf(T t, Predicate<V> pred);
+
     V max(T t);
 
     V secondMax(T t);
@@ -43,7 +46,7 @@ public interface OrderedTreeProcessor<V, T> {
 
     T leftmostNodeInRightSubtree(T t);
 
-    T invert(T t);
+    void invert(T t);
 
     T clone(T t);
 

src/main/java/aud/exam/prep/tree/RecursiveOrderedBinaryTreeNodeProcessor.java

@@ -3,6 +3,7 @@ package aud.exam.prep.tree;
 import aud.exam.prep.Pointer;
 
 import java.util.Comparator;
+import java.util.function.Predicate;
 
 public class RecursiveOrderedBinaryTreeNodeProcessor<V> extends OrderedBinaryTreeNodeProcessor<V> {
 
@@ -221,6 +222,42 @@ public class RecursiveOrderedBinaryTreeNodeProcessor<V> extends OrderedBinaryTre
         return removeAllWithCountRec(node.right, v, cmp, node, true);
     }
 
+    @Override
+    public BinaryTreeNode<V> removeIf(BinaryTreeNode<V> root, Predicate<V> pred) {
+        if (root == null) {
+            return null;
+        }
+        root.left = removeIf(root.left, pred);
+        root.right = removeIf(root.right, pred);
+
+        if (pred.test(root.key)) {
+
+            if (root.left == null) {
+                return root.right;
+            } else if (root.right == null) {
+                return root.left;
+            } else {
+                root.key = removeRightMostNode(root.left, root, false);
+            }
+        }
+
+        return root;
+    }
+
+    V removeRightMostNode(BinaryTreeNode<V> node, BinaryTreeNode<V> prev, boolean right) {
+        if (node.right != null) {
+            return removeRightMostNode(node.right, node, true);
+        }
+
+        if (right) {
+            prev.right = node.left;
+        } else {
+            prev.left = node.left;
+        }
+
+        return node.key;
+    }
+
     @Override
     public V max(BinaryTreeNode<V> tree) {
         if (tree == null) {
@@ -273,10 +310,7 @@ public class RecursiveOrderedBinaryTreeNodeProcessor<V> extends OrderedBinaryTre
 
     @Override
     public boolean isBalanced(BinaryTreeNode<V> tree) {
-        if (tree == null) {
-            return true;
-        }
-        return false;
+        return tree == null;
     }
 
     @Override
@@ -300,13 +334,31 @@ public class RecursiveOrderedBinaryTreeNodeProcessor<V> extends OrderedBinaryTre
     }
 
     @Override
-    public BinaryTreeNode<V> invert(BinaryTreeNode<V> tree) {
-        return null;
+    public void invert(BinaryTreeNode<V> tree) {
+        if (tree == null) {
+            return;
+        }
+
+        invert(tree.left);
+        invert(tree.right);
+
+        var t = tree.left;
+        tree.left = tree.right;
+        tree.right = t;
     }
 
     @Override
     public BinaryTreeNode<V> clone(BinaryTreeNode<V> tree) {
-        return null;
+        if (tree == null) {
+            return null;
+        }
+
+        var t = new BinaryTreeNode<V>();
+        t.left = clone(tree.left);
+        t.right = clone(tree.right);
+        t.key = tree.key;
+
+        return t;
     }
 
     @Override
@@ -331,4 +383,26 @@ public class RecursiveOrderedBinaryTreeNodeProcessor<V> extends OrderedBinaryTre
 
         return true;
     }
+
+    @Override
+    public void print(BinaryTreeNode<V> tree) {
+        printRec(tree, 0);
+    }
+
+    private void printRec(BinaryTreeNode<V> tree, int indent) {
+        if (tree == null) {
+            System.out.println("- *");
+            return;
+        }
+
+        System.out.println("-> " + tree.key);
+
+        System.out.print(" |".repeat(indent));
+        System.out.print(" L");
+        printRec(tree.left, indent + 1);
+
+        System.out.print(" |".repeat(indent));
+        System.out.print(" L");
+        printRec(tree.right, indent + 1);
+    }
 }

src/test/java/aud/exam/prep/DoubleLatinProvider.java

@@ -10,7 +10,7 @@ import java.util.stream.Stream;
 public class DoubleLatinProvider implements ArgumentsProvider {
 
     @Override
-    public Stream<? extends Arguments> provideArguments(ExtensionContext extensionContext) throws Exception {
+    public Stream<? extends Arguments> provideArguments(ExtensionContext extensionContext) {
         return Stream
             .generate(() ->
                 Arguments.of(randomLatin(), randomLatin()))

src/test/java/aud/exam/prep/list/DoubleListItemProcessorTest.java

@@ -0,0 +1,51 @@
+package aud.exam.prep.list;
+
+import aud.exam.prep.SequenceProcessor;
+import aud.exam.prep.SequenceProcessorTest;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+abstract class DoubleListItemProcessorTest extends SequenceProcessorTest<DoubleListItem<Integer>> {
+
+    protected DoubleListItemProcessorTest(SequenceProcessor<Integer, DoubleListItem<Integer>> processor) {
+        super(processor);
+    }
+
+    @Test
+    void testThat_checkOfNullIsTrue() {
+        assertTrue(processor.check(null));
+    }
+
+    @Test
+    void testThat_checkOfNoKeyIsFalse() {
+        var item = new DoubleListItem<Integer>();
+        assertFalse(processor.check(item));
+    }
+
+    @Test
+    void testThat_checkOfNoPrevOfNextIsFalse() {
+        var item = new DoubleListItem<Integer>();
+        item.key = 1;
+
+        item.next = new DoubleListItem<>();
+        item.next.key = 1;
+
+        assertFalse(processor.check(item));
+    }
+
+    @Test
+    void testThat_checkOfCircleIsFalse() {
+        var item = new DoubleListItem<Integer>();
+        item.next = item;
+        assertFalse(processor.check(item));
+    }
+
+    @Test
+    void testThat_checkPrevNextNotMatchingIsFalse() {
+        var item = new DoubleListItem<Integer>();
+        item.next = new DoubleListItem<>();
+        item.next.prev = new DoubleListItem<>();
+        assertFalse(processor.check(item));
+    }
+}

src/test/java/aud/exam/prep/list/IterativeDoubleListItemProcessorTest.java

@@ -0,0 +1,10 @@
+package aud.exam.prep.list;
+
+import aud.exam.prep.SequenceProcessorTest;
+
+class IterativeDoubleListItemProcessorTest extends SequenceProcessorTest<DoubleListItem<Integer>> {
+
+    protected IterativeDoubleListItemProcessorTest() {
+        super(new IterativeDoubleListItemProcessor<>());
+    }
+}

src/test/java/aud/exam/prep/list/IterativeSingleListItemProcessorTest.java

@@ -0,0 +1,10 @@
+package aud.exam.prep.list;
+
+import aud.exam.prep.SequenceProcessorTest;
+
+class IterativeSingleListItemProcessorTest extends SequenceProcessorTest<SingleListItem<Integer>> {
+
+    protected IterativeSingleListItemProcessorTest() {
+        super(new IterativeSingleListItemProcessor<>());
+    }
+}

src/test/java/aud/exam/prep/list/RecursiveDoubleListItemProcessorTest.java

@@ -0,0 +1,8 @@
+package aud.exam.prep.list;
+
+public class RecursiveDoubleListItemProcessorTest extends DoubleListItemProcessorTest {
+
+    protected RecursiveDoubleListItemProcessorTest() {
+        super(new RecursiveDoubleListItemProcessor<>());
+    }
+}

src/test/java/aud/exam/prep/list/RecursiveSingleListItemProcessorTest.java

@@ -0,0 +1,10 @@
+package aud.exam.prep.list;
+
+import aud.exam.prep.SequenceProcessorTest;
+
+class RecursiveSingleListItemProcessorTest extends SequenceProcessorTest<SingleListItem<Integer>> {
+
+    protected RecursiveSingleListItemProcessorTest() {
+        super(new RecursiveSingleListItemProcessor<>());
+    }
+}

src/test/java/aud/exam/prep/tree/OrderedTreeProcessorTest.java

@@ -10,6 +10,9 @@ import org.junit.jupiter.params.provider.ArgumentsSource;
 import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
+import java.util.function.Predicate;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
 
 import static aud.exam.prep.Tests.CMP;
 import static org.junit.jupiter.api.Assertions.*;
@@ -69,7 +72,7 @@ public abstract class OrderedTreeProcessorTest<T> {
         assertIterableEquals(list, processor.iterate(t));
     }
 
-    private T asTree(List<Integer> list) {
+    protected T asTree(List<Integer> list) {
         T t = processor.newEmptyTree();
 
         for (var n : list) {
@@ -168,6 +171,46 @@ public abstract class OrderedTreeProcessorTest<T> {
         }
     }
 
+    @ParameterizedTest
+    @ArgumentsSource(ListProvider.class)
+    void testThat_removeIfWorks(List<Integer> list) {
+        T t = asTree(list);
+        list.sort(CMP);
+
+        for (var toRemove : getRemovals(list)) {
+            Predicate<Integer> pred = n ->
+                    Objects.equals(n, toRemove);
+
+            list.removeIf(pred);
+
+            t = processor.removeIf(t, pred);
+
+            assertTrue(processor.check(t, CMP));
+            assertIterableEquals(list, processor.iterate(t));
+        }
+    }
+
+    List<Integer> getRemovals(List<Integer> list) {
+        var start = -100 + list
+                .stream()
+                .min(CMP)
+                .orElse(0);
+
+        var end = 100 + list
+                .stream()
+                .max(CMP)
+                .orElse(0);
+
+        var removals = IntStream
+                .rangeClosed(start, end)
+                .boxed()
+                .collect(Collectors.toList());
+
+        Collections.shuffle(removals, Tests.RANDOM);
+
+        return removals;
+    }
+
     @ParameterizedTest
     @ArgumentsSource(ListProvider.class)
     void printATree(List<Integer> list) {
@@ -243,4 +286,28 @@ public abstract class OrderedTreeProcessorTest<T> {
             assertIterableEquals(list, processor.iterate(t));
         }
     }
+
+    @ParameterizedTest
+    @ArgumentsSource(ListProvider.class)
+    void testThat_invertWorks(List<Integer> list) {
+        T t = asTree(list);
+        processor.invert(t);
+
+        var cmp = CMP.reversed();
+
+        assertTrue(processor.check(t, cmp));
+        list.sort(cmp);
+        assertIterableEquals(list, processor.iterate(t));
+    }
+
+    @ParameterizedTest
+    @ArgumentsSource(ListProvider.class)
+    void testThat_cloneWorks(List<Integer> list) {
+        T t = asTree(list);
+        t = processor.clone(t);
+
+        assertTrue(processor.check(t, CMP));
+        list.sort(CMP);
+        assertIterableEquals(list, processor.iterate(t));
+    }
 }