Merge branch 'master' into ddaline

Author: DenizAltunkapan

.github/workflows/codeql.yml

@@ -30,15 +30,15 @@ jobs:
           distribution: 'temurin'
 
       - name: Initialize CodeQL
-        uses: github/codeql-action/init@v3
+        uses: github/codeql-action/init@v4
         with:
           languages: 'java-kotlin'
 
       - name: Build
         run: mvn --batch-mode --update-snapshots verify
 
       - name: Perform CodeQL Analysis
-        uses: github/codeql-action/analyze@v3
+        uses: github/codeql-action/analyze@v4
         with:
           category: "/language:java-kotlin"
 
@@ -55,12 +55,12 @@ jobs:
         uses: actions/checkout@v5
 
       - name: Initialize CodeQL
-        uses: github/codeql-action/init@v3
+        uses: github/codeql-action/init@v4
         with:
           languages: 'actions'
 
       - name: Perform CodeQL Analysis
-        uses: github/codeql-action/analyze@v3
+        uses: github/codeql-action/analyze@v4
         with:
           category: "/language:actions"
 ...

.gitpod.dockerfile

@@ -1,4 +1,4 @@
-FROM gitpod/workspace-java-21:2025-08-25-18-17-39
+FROM gitpod/workspace-java-21:2025-10-06-13-14-25
 
 ENV LLVM_SCRIPT="tmp_llvm.sh"
 

DIRECTORY.md

@@ -173,6 +173,7 @@
             - 📄 [TarjansAlgorithm](src/main/java/com/thealgorithms/datastructures/graphs/TarjansAlgorithm.java)
             - 📄 [UndirectedAdjacencyListGraph](src/main/java/com/thealgorithms/datastructures/graphs/UndirectedAdjacencyListGraph.java)
             - 📄 [WelshPowell](src/main/java/com/thealgorithms/datastructures/graphs/WelshPowell.java)
+            - 📄 [TwoSat](src/main/java/com/thealgorithms/datastructures/graphs/TwoSat.java)
           - 📁 **hashmap**
             - 📁 **hashing**
               - 📄 [GenericHashMapUsingArray](src/main/java/com/thealgorithms/datastructures/hashmap/hashing/GenericHashMapUsingArray.java)
@@ -352,6 +353,8 @@
           - 📄 [PredecessorConstrainedDfs](src/main/java/com/thealgorithms/graph/PredecessorConstrainedDfs.java)
           - 📄 [StronglyConnectedComponentOptimized](src/main/java/com/thealgorithms/graph/StronglyConnectedComponentOptimized.java)
           - 📄 [TravelingSalesman](src/main/java/com/thealgorithms/graph/TravelingSalesman.java)
+          - 📄 [Dinic](src/main/java/com/thealgorithms/graph/Dinic.java)
+          - 📄 [YensKShortestPaths](src/main/java/com/thealgorithms/graph/YensKShortestPaths.java)
         - 📁 **greedyalgorithms**
           - 📄 [ActivitySelection](src/main/java/com/thealgorithms/greedyalgorithms/ActivitySelection.java)
           - 📄 [BandwidthAllocation](src/main/java/com/thealgorithms/greedyalgorithms/BandwidthAllocation.java)

pmd-exclude.properties

@@ -88,12 +88,14 @@ com.thealgorithms.others.LinearCongruentialGenerator=UselessMainMethod
 com.thealgorithms.others.Luhn=UnnecessaryFullyQualifiedName,UselessMainMethod
 com.thealgorithms.others.Mandelbrot=UselessMainMethod,UselessParentheses
 com.thealgorithms.others.MiniMaxAlgorithm=UselessMainMethod,UselessParentheses
+com.thealgorithms.others.MosAlgorithm=UselessMainMethod
 com.thealgorithms.others.PageRank=UselessMainMethod,UselessParentheses
 com.thealgorithms.others.PerlinNoise=UselessMainMethod,UselessParentheses
 com.thealgorithms.others.QueueUsingTwoStacks=UselessParentheses
 com.thealgorithms.others.Trieac=UselessMainMethod,UselessParentheses
 com.thealgorithms.others.Verhoeff=UnnecessaryFullyQualifiedName,UselessMainMethod
 com.thealgorithms.puzzlesandgames.Sudoku=UselessMainMethod
+com.thealgorithms.recursion.DiceThrower=UselessMainMethod
 com.thealgorithms.searches.HowManyTimesRotated=UselessMainMethod
 com.thealgorithms.searches.InterpolationSearch=UselessParentheses
 com.thealgorithms.searches.KMPSearch=UselessParentheses

pom.xml

@@ -71,8 +71,7 @@
                 <artifactId>maven-compiler-plugin</artifactId>
                 <version>3.14.1</version>
                 <configuration>
-                    <source>21</source>
-                    <target>21</target>
+                    <release>21</release>
                     <compilerArgs>
                         <arg>-Xlint:all</arg>
                         <arg>-Xlint:-auxiliaryclass</arg>
@@ -83,7 +82,7 @@
             <plugin>
                 <groupId>org.jacoco</groupId>
                 <artifactId>jacoco-maven-plugin</artifactId>
-                <version>0.8.13</version>
+                <version>0.8.14</version>
                 <executions>
                     <execution>
                         <goals>
@@ -113,7 +112,7 @@
                     <dependency>
                     <groupId>com.puppycrawl.tools</groupId>
                     <artifactId>checkstyle</artifactId>
-                    <version>11.1.0</version>
+                    <version>12.0.1</version>
                     </dependency>
                 </dependencies>
             </plugin>
@@ -128,7 +127,7 @@
                         <plugin>
                             <groupId>com.mebigfatguy.fb-contrib</groupId>
                             <artifactId>fb-contrib</artifactId>
-                            <version>7.6.14</version>
+                            <version>7.6.15</version>
                         </plugin>
                         <plugin>
                             <groupId>com.h3xstream.findsecbugs</groupId>
@@ -141,7 +140,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-pmd-plugin</artifactId>
-                <version>3.27.0</version>
+                <version>3.28.0</version>
                 <configuration>
                     <rulesets>
                         <ruleset>/rulesets/java/maven-pmd-plugin-default.xml</ruleset>

src/main/java/com/thealgorithms/ciphers/PermutationCipher.java

@@ -0,0 +1,194 @@
+package com.thealgorithms.ciphers;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * A Java implementation of Permutation Cipher.
+ * It is a type of transposition cipher in which the plaintext is divided into blocks
+ * and the characters within each block are rearranged according to a fixed permutation key.
+ *
+ * For example, with key {3, 1, 2} and plaintext "HELLO", the text is divided into blocks
+ * of 3 characters: "HEL" and "LO" (with padding). The characters are then rearranged
+ * according to the key positions.
+ *
+ * @author GitHub Copilot
+ */
+public class PermutationCipher {
+
+    private static final char PADDING_CHAR = 'X';
+
+    /**
+     * Encrypts the given plaintext using the permutation cipher with the specified key.
+     *
+     * @param plaintext the text to encrypt
+     * @param key the permutation key (array of integers representing positions)
+     * @return the encrypted text
+     * @throws IllegalArgumentException if the key is invalid
+     */
+    public String encrypt(String plaintext, int[] key) {
+        validateKey(key);
+
+        if (plaintext == null || plaintext.isEmpty()) {
+            return plaintext;
+        }
+
+        // Remove spaces and convert to uppercase for consistent processing
+        String cleanText = plaintext.replaceAll("\\s+", "").toUpperCase();
+
+        // Pad the text to make it divisible by key length
+        String paddedText = padText(cleanText, key.length);
+
+        StringBuilder encrypted = new StringBuilder();
+
+        // Process text in blocks of key length
+        for (int i = 0; i < paddedText.length(); i += key.length) {
+            String block = paddedText.substring(i, Math.min(i + key.length, paddedText.length()));
+            encrypted.append(permuteBlock(block, key));
+        }
+
+        return encrypted.toString();
+    }
+
+    /**
+     * Decrypts the given ciphertext using the permutation cipher with the specified key.
+     *
+     * @param ciphertext the text to decrypt
+     * @param key the permutation key (array of integers representing positions)
+     * @return the decrypted text
+     * @throws IllegalArgumentException if the key is invalid
+     */
+    public String decrypt(String ciphertext, int[] key) {
+        validateKey(key);
+
+        if (ciphertext == null || ciphertext.isEmpty()) {
+            return ciphertext;
+        }
+
+        // Create the inverse permutation
+        int[] inverseKey = createInverseKey(key);
+
+        StringBuilder decrypted = new StringBuilder();
+
+        // Process text in blocks of key length
+        for (int i = 0; i < ciphertext.length(); i += key.length) {
+            String block = ciphertext.substring(i, Math.min(i + key.length, ciphertext.length()));
+            decrypted.append(permuteBlock(block, inverseKey));
+        }
+
+        // Remove padding characters from the end
+        return removePadding(decrypted.toString());
+    }
+    /**
+     * Validates that the permutation key is valid.
+     * A valid key must contain all integers from 1 to n exactly once, where n is the key length.
+     *
+     * @param key the permutation key to validate
+     * @throws IllegalArgumentException if the key is invalid
+     */
+    private void validateKey(int[] key) {
+        if (key == null || key.length == 0) {
+            throw new IllegalArgumentException("Key cannot be null or empty");
+        }
+
+        Set<Integer> keySet = new HashSet<>();
+        for (int position : key) {
+            if (position < 1 || position > key.length) {
+                throw new IllegalArgumentException("Key must contain integers from 1 to " + key.length);
+            }
+            if (!keySet.add(position)) {
+                throw new IllegalArgumentException("Key must contain each position exactly once");
+            }
+        }
+    }
+
+    /**
+     * Pads the text with padding characters to make its length divisible by the block size.
+     *
+     * @param text the text to pad
+     * @param blockSize the size of each block
+     * @return the padded text
+     */
+    private String padText(String text, int blockSize) {
+        int remainder = text.length() % blockSize;
+        if (remainder == 0) {
+            return text;
+        }
+
+        int paddingNeeded = blockSize - remainder;
+        StringBuilder padded = new StringBuilder(text);
+        for (int i = 0; i < paddingNeeded; i++) {
+            padded.append(PADDING_CHAR);
+        }
+
+        return padded.toString();
+    }
+    /**
+     * Applies the permutation to a single block of text.
+     *
+     * @param block the block to permute
+     * @param key the permutation key
+     * @return the permuted block
+     */
+    private String permuteBlock(String block, int[] key) {
+        if (block.length() != key.length) {
+            // Handle case where block is shorter than key (shouldn't happen with proper padding)
+            block = padText(block, key.length);
+        }
+
+        char[] result = new char[key.length];
+        char[] blockChars = block.toCharArray();
+
+        for (int i = 0; i < key.length; i++) {
+            // Key positions are 1-based, so subtract 1 for 0-based array indexing
+            result[i] = blockChars[key[i] - 1];
+        }
+
+        return new String(result);
+    }
+
+    /**
+     * Creates the inverse permutation key for decryption.
+     *
+     * @param key the original permutation key
+     * @return the inverse key
+     */
+    private int[] createInverseKey(int[] key) {
+        int[] inverse = new int[key.length];
+
+        for (int i = 0; i < key.length; i++) {
+            // The inverse key maps each position to where it should go
+            inverse[key[i] - 1] = i + 1;
+        }
+
+        return inverse;
+    }
+
+    /**
+     * Removes padding characters from the end of the decrypted text.
+     *
+     * @param text the text to remove padding from
+     * @return the text without padding
+     */
+    private String removePadding(String text) {
+        if (text.isEmpty()) {
+            return text;
+        }
+
+        int i = text.length() - 1;
+        while (i >= 0 && text.charAt(i) == PADDING_CHAR) {
+            i--;
+        }
+
+        return text.substring(0, i + 1);
+    }
+
+    /**
+     * Gets the padding character used by this cipher.
+     *
+     * @return the padding character
+     */
+    public char getPaddingChar() {
+        return PADDING_CHAR;
+    }
+}

src/main/java/com/thealgorithms/compression/RunLengthEncoding.java

@@ -0,0 +1,87 @@
+package com.thealgorithms.compression;
+
+/**
+ * An implementation of the Run-Length Encoding (RLE) algorithm.
+ *
+ * <p>Run-Length Encoding is a simple form of lossless data compression in which
+ * runs of data (sequences in which the same data value occurs in many
+ * consecutive data elements) are stored as a single data value and count,
+ * rather than as the original run.
+ *
+ * <p>This implementation provides methods for both compressing and decompressing
+ * a string. For example:
+ * <ul>
+ * <li>Compressing "AAAABBBCCDAA" results in "4A3B2C1D2A".</li>
+ * <li>Decompressing "4A3B2C1D2A" results in "AAAABBBCCDAA".</li>
+ * </ul>
+ *
+ * <p>Time Complexity: O(n) for both compression and decompression, where n is the
+ * length of the input string.
+ *
+ * <p>References:
+ * <ul>
+ * <li><a href="https://en.wikipedia.org/wiki/Run-length_encoding">Wikipedia: Run-length encoding</a></li>
+ * </ul>
+ */
+public final class RunLengthEncoding {
+
+    /**
+     * Private constructor to prevent instantiation of this utility class.
+     */
+    private RunLengthEncoding() {
+    }
+
+    /**
+     * Compresses a string using the Run-Length Encoding algorithm.
+     *
+     * @param text The string to be compressed. Must not be null.
+     * @return The compressed string. Returns an empty string if the input is empty.
+     */
+    public static String compress(String text) {
+        if (text == null || text.isEmpty()) {
+            return "";
+        }
+
+        StringBuilder compressed = new StringBuilder();
+        int count = 1;
+
+        for (int i = 0; i < text.length(); i++) {
+            // Check if it's the last character or if the next character is different
+            if (i == text.length() - 1 || text.charAt(i) != text.charAt(i + 1)) {
+                compressed.append(count);
+                compressed.append(text.charAt(i));
+                count = 1; // Reset count for the new character
+            } else {
+                count++;
+            }
+        }
+        return compressed.toString();
+    }
+
+    /**
+     * Decompresses a string that was compressed using the Run-Length Encoding algorithm.
+     *
+     * @param compressedText The compressed string. Must not be null.
+     * @return The original, uncompressed string.
+     */
+    public static String decompress(String compressedText) {
+        if (compressedText == null || compressedText.isEmpty()) {
+            return "";
+        }
+
+        StringBuilder decompressed = new StringBuilder();
+        int count = 0;
+
+        for (char ch : compressedText.toCharArray()) {
+            if (Character.isDigit(ch)) {
+                // Build the number for runs of 10 or more (e.g., "12A")
+                count = count * 10 + ch - '0';
+            } else {
+                // Append the character 'count' times
+                decompressed.append(String.valueOf(ch).repeat(Math.max(0, count)));
+                count = 0; // Reset count for the next sequence
+            }
+        }
+        return decompressed.toString();
+    }
+}