Merge branch 'master' into add-elgamal-encryption

Author: polasisubash

.github/workflows/build.yml

@@ -8,7 +8,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up JDK
         uses: actions/setup-java@v5
         with:

.github/workflows/clang-format-lint.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - uses: DoozyX/clang-format-lint-action@v0.20
       with:
         source: './src'

.github/workflows/codeql.yml

@@ -21,7 +21,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Set up JDK
         uses: actions/setup-java@v5
@@ -52,7 +52,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Initialize CodeQL
         uses: github/codeql-action/init@v4

.github/workflows/infer.yml

@@ -15,7 +15,7 @@ jobs:
   run_infer:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Set up JDK
         uses: actions/setup-java@v5
@@ -44,7 +44,7 @@ jobs:
           cd ..
           git clone https://github.com/facebook/infer.git
           cd infer
-          git checkout 01aaa268f9d38723ba69c139e10f9e2a04b40b1c
+          git checkout 02c2c43b71e4c5110c0be841e66153942fda06c9
           ./build-infer.sh java
           cp -r infer ../Java
 

.github/workflows/project_structure.yml

@@ -15,7 +15,7 @@ jobs:
   check_structure:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/setup-python@v6
         with:
           python-version: '3.13'

.github/workflows/update-directorymd.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Run Directory Tree Generator
         uses: DenizAltunkapan/directory-tree-generator@v2

.inferconfig

@@ -1,22 +1,27 @@
 {
     "report-block-list-path-regex": [
         "src/main/java/com/thealgorithms/ciphers/a5/CompositeLFSR.java",
+        "src/main/java/com/thealgorithms/compression/ArithmeticCoding.java",
+        "src/main/java/com/thealgorithms/datastructures/caches/FIFOCache.java",
         "src/main/java/com/thealgorithms/datastructures/crdt/GCounter.java",
         "src/main/java/com/thealgorithms/datastructures/crdt/PNCounter.java",
         "src/main/java/com/thealgorithms/datastructures/graphs/KahnsAlgorithm.java",
         "src/main/java/com/thealgorithms/datastructures/heaps/GenericHeap.java",
         "src/main/java/com/thealgorithms/datastructures/lists/DoublyLinkedList.java",
         "src/main/java/com/thealgorithms/datastructures/trees/CreateBinaryTreeFromInorderPreorder.java",
         "src/main/java/com/thealgorithms/divideandconquer/ClosestPair.java",
+        "src/main/java/com/thealgorithms/dynamicprogramming/DamerauLevenshteinDistance.java",
         "src/main/java/com/thealgorithms/dynamicprogramming/Fibonacci.java",
         "src/main/java/com/thealgorithms/maths/SimpsonIntegration.java",
         "src/main/java/com/thealgorithms/others/Dijkstra.java",
         "src/main/java/com/thealgorithms/sorts/TopologicalSort.java",
         "src/main/java/com/thealgorithms/strings/AhoCorasick.java",
+        "src/test/java/com/thealgorithms/compression/ShannonFanoTest.java",
         "src/test/java/com/thealgorithms/datastructures/caches/LRUCacheTest.java",
         "src/test/java/com/thealgorithms/datastructures/lists/SkipListTest.java",
         "src/test/java/com/thealgorithms/datastructures/trees/KDTreeTest.java",
         "src/test/java/com/thealgorithms/datastructures/trees/LazySegmentTreeTest.java",
+        "src/test/java/com/thealgorithms/others/HuffmanTest.java",
         "src/test/java/com/thealgorithms/searches/QuickSelectTest.java",
         "src/test/java/com/thealgorithms/stacks/PostfixToInfixTest.java",
         "src/test/java/com/thealgorithms/strings/HorspoolSearchTest.java"

DIRECTORY.md

@@ -24,6 +24,8 @@
           - 📄 [Permutation](src/main/java/com/thealgorithms/backtracking/Permutation.java)
           - 📄 [PowerSum](src/main/java/com/thealgorithms/backtracking/PowerSum.java)
           - 📄 [SubsequenceFinder](src/main/java/com/thealgorithms/backtracking/SubsequenceFinder.java)
+          - 📄 [SudokuSolver](src/main/java/com/thealgorithms/backtracking/SudokuSolver.java)
+          - 📄 [UniquePermutation](src/main/java/com/thealgorithms/backtracking/UniquePermutation.java)
           - 📄 [WordPatternMatcher](src/main/java/com/thealgorithms/backtracking/WordPatternMatcher.java)
           - 📄 [WordSearch](src/main/java/com/thealgorithms/backtracking/WordSearch.java)
         - 📁 **bitmanipulation**
@@ -133,6 +135,7 @@
           - 📄 [PhoneticAlphabetConverter](src/main/java/com/thealgorithms/conversions/PhoneticAlphabetConverter.java)
           - 📄 [RgbHsvConversion](src/main/java/com/thealgorithms/conversions/RgbHsvConversion.java)
           - 📄 [RomanToInteger](src/main/java/com/thealgorithms/conversions/RomanToInteger.java)
+          - 📄 [TemperatureConverter](src/main/java/com/thealgorithms/conversions/TemperatureConverter.java)
           - 📄 [TimeConverter](src/main/java/com/thealgorithms/conversions/TimeConverter.java)
           - 📄 [TurkishToLatinConversion](src/main/java/com/thealgorithms/conversions/TurkishToLatinConversion.java)
           - 📄 [UnitConversions](src/main/java/com/thealgorithms/conversions/UnitConversions.java)
@@ -208,6 +211,7 @@
             - 📄 [GenericHeap](src/main/java/com/thealgorithms/datastructures/heaps/GenericHeap.java)
             - 📄 [Heap](src/main/java/com/thealgorithms/datastructures/heaps/Heap.java)
             - 📄 [HeapElement](src/main/java/com/thealgorithms/datastructures/heaps/HeapElement.java)
+            - 📄 [IndexedPriorityQueue](src/main/java/com/thealgorithms/datastructures/heaps/IndexedPriorityQueue.java)
             - 📄 [KthElementFinder](src/main/java/com/thealgorithms/datastructures/heaps/KthElementFinder.java)
             - 📄 [LeftistHeap](src/main/java/com/thealgorithms/datastructures/heaps/LeftistHeap.java)
             - 📄 [MaxHeap](src/main/java/com/thealgorithms/datastructures/heaps/MaxHeap.java)
@@ -507,6 +511,7 @@
           - 📄 [PiNilakantha](src/main/java/com/thealgorithms/maths/PiNilakantha.java)
           - 📄 [PollardRho](src/main/java/com/thealgorithms/maths/PollardRho.java)
           - 📄 [Pow](src/main/java/com/thealgorithms/maths/Pow.java)
+          - 📄 [PowerOfFour](src/main/java/com/thealgorithms/maths/PowerOfFour.java)
           - 📄 [PowerOfTwoOrNot](src/main/java/com/thealgorithms/maths/PowerOfTwoOrNot.java)
           - 📄 [PowerUsingRecursion](src/main/java/com/thealgorithms/maths/PowerUsingRecursion.java)
           - 📁 **Prime**
@@ -525,6 +530,7 @@
           - 📄 [SieveOfAtkin](src/main/java/com/thealgorithms/maths/SieveOfAtkin.java)
           - 📄 [SieveOfEratosthenes](src/main/java/com/thealgorithms/maths/SieveOfEratosthenes.java)
           - 📄 [SimpsonIntegration](src/main/java/com/thealgorithms/maths/SimpsonIntegration.java)
+          - 📄 [SmithNumber](src/main/java/com/thealgorithms/maths/SmithNumber.java)
           - 📄 [SolovayStrassenPrimalityTest](src/main/java/com/thealgorithms/maths/SolovayStrassenPrimalityTest.java)
           - 📄 [SquareRootWithBabylonianMethod](src/main/java/com/thealgorithms/maths/SquareRootWithBabylonianMethod.java)
           - 📄 [SquareRootWithNewtonRaphsonMethod](src/main/java/com/thealgorithms/maths/SquareRootWithNewtonRaphsonMethod.java)
@@ -622,7 +628,6 @@
           - 📄 [ProjectileMotion](src/main/java/com/thealgorithms/physics/ProjectileMotion.java)
           - 📄 [SimplePendulumRK4](src/main/java/com/thealgorithms/physics/SimplePendulumRK4.java)
         - 📁 **puzzlesandgames**
-          - 📄 [Sudoku](src/main/java/com/thealgorithms/puzzlesandgames/Sudoku.java)
           - 📄 [TowerOfHanoi](src/main/java/com/thealgorithms/puzzlesandgames/TowerOfHanoi.java)
           - 📄 [WordBoggle](src/main/java/com/thealgorithms/puzzlesandgames/WordBoggle.java)
         - 📁 **randomized**
@@ -842,6 +847,8 @@
           - 📄 [PermutationTest](src/test/java/com/thealgorithms/backtracking/PermutationTest.java)
           - 📄 [PowerSumTest](src/test/java/com/thealgorithms/backtracking/PowerSumTest.java)
           - 📄 [SubsequenceFinderTest](src/test/java/com/thealgorithms/backtracking/SubsequenceFinderTest.java)
+          - 📄 [SudokuSolverTest](src/test/java/com/thealgorithms/backtracking/SudokuSolverTest.java)
+          - 📄 [UniquePermutationTest](src/test/java/com/thealgorithms/backtracking/UniquePermutationTest.java)
           - 📄 [WordPatternMatcherTest](src/test/java/com/thealgorithms/backtracking/WordPatternMatcherTest.java)
           - 📄 [WordSearchTest](src/test/java/com/thealgorithms/backtracking/WordSearchTest.java)
         - 📁 **bitmanipulation**
@@ -944,6 +951,7 @@
           - 📄 [OctalToHexadecimalTest](src/test/java/com/thealgorithms/conversions/OctalToHexadecimalTest.java)
           - 📄 [PhoneticAlphabetConverterTest](src/test/java/com/thealgorithms/conversions/PhoneticAlphabetConverterTest.java)
           - 📄 [RomanToIntegerTest](src/test/java/com/thealgorithms/conversions/RomanToIntegerTest.java)
+          - 📄 [TemperatureConverterTest](src/test/java/com/thealgorithms/conversions/TemperatureConverterTest.java)
           - 📄 [TimeConverterTest](src/test/java/com/thealgorithms/conversions/TimeConverterTest.java)
           - 📄 [TurkishToLatinConversionTest](src/test/java/com/thealgorithms/conversions/TurkishToLatinConversionTest.java)
           - 📄 [UnitConversionsTest](src/test/java/com/thealgorithms/conversions/UnitConversionsTest.java)
@@ -1009,6 +1017,7 @@
             - 📄 [FibonacciHeapTest](src/test/java/com/thealgorithms/datastructures/heaps/FibonacciHeapTest.java)
             - 📄 [GenericHeapTest](src/test/java/com/thealgorithms/datastructures/heaps/GenericHeapTest.java)
             - 📄 [HeapElementTest](src/test/java/com/thealgorithms/datastructures/heaps/HeapElementTest.java)
+            - 📄 [IndexedPriorityQueueTest](src/test/java/com/thealgorithms/datastructures/heaps/IndexedPriorityQueueTest.java)
             - 📄 [KthElementFinderTest](src/test/java/com/thealgorithms/datastructures/heaps/KthElementFinderTest.java)
             - 📄 [LeftistHeapTest](src/test/java/com/thealgorithms/datastructures/heaps/LeftistHeapTest.java)
             - 📄 [MaxHeapTest](src/test/java/com/thealgorithms/datastructures/heaps/MaxHeapTest.java)
@@ -1279,6 +1288,7 @@
           - 📄 [PiApproximationTest](src/test/java/com/thealgorithms/maths/PiApproximationTest.java)
           - 📄 [PollardRhoTest](src/test/java/com/thealgorithms/maths/PollardRhoTest.java)
           - 📄 [PowTest](src/test/java/com/thealgorithms/maths/PowTest.java)
+          - 📄 [PowerOfFourTest](src/test/java/com/thealgorithms/maths/PowerOfFourTest.java)
           - 📄 [PowerOfTwoOrNotTest](src/test/java/com/thealgorithms/maths/PowerOfTwoOrNotTest.java)
           - 📄 [PowerUsingRecursionTest](src/test/java/com/thealgorithms/maths/PowerUsingRecursionTest.java)
           - 📄 [PronicNumberTest](src/test/java/com/thealgorithms/maths/PronicNumberTest.java)
@@ -1288,6 +1298,7 @@
           - 📄 [SecondMinMaxTest](src/test/java/com/thealgorithms/maths/SecondMinMaxTest.java)
           - 📄 [SieveOfAtkinTest](src/test/java/com/thealgorithms/maths/SieveOfAtkinTest.java)
           - 📄 [SieveOfEratosthenesTest](src/test/java/com/thealgorithms/maths/SieveOfEratosthenesTest.java)
+          - 📄 [SmithNumberTest](src/test/java/com/thealgorithms/maths/SmithNumberTest.java)
           - 📄 [SolovayStrassenPrimalityTestTest](src/test/java/com/thealgorithms/maths/SolovayStrassenPrimalityTestTest.java)
           - 📄 [SquareFreeIntegerTest](src/test/java/com/thealgorithms/maths/SquareFreeIntegerTest.java)
           - 📄 [SquareRootWithNewtonRaphsonTestMethod](src/test/java/com/thealgorithms/maths/SquareRootWithNewtonRaphsonTestMethod.java)
@@ -1377,7 +1388,6 @@
           - 📄 [ProjectileMotionTest](src/test/java/com/thealgorithms/physics/ProjectileMotionTest.java)
           - 📄 [SimplePendulumRK4Test](src/test/java/com/thealgorithms/physics/SimplePendulumRK4Test.java)
         - 📁 **puzzlesandgames**
-          - 📄 [SudokuTest](src/test/java/com/thealgorithms/puzzlesandgames/SudokuTest.java)
           - 📄 [TowerOfHanoiTest](src/test/java/com/thealgorithms/puzzlesandgames/TowerOfHanoiTest.java)
           - 📄 [WordBoggleTest](src/test/java/com/thealgorithms/puzzlesandgames/WordBoggleTest.java)
         - 📁 **randomized**

pom.xml

@@ -48,7 +48,7 @@
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-lang3</artifactId>
-            <version>3.19.0</version>
+            <version>3.20.0</version>
         </dependency>
         <dependency>
             <groupId>org.apache.commons</groupId>

src/main/java/com/thealgorithms/backtracking/SudokuSolver.java

@@ -0,0 +1,157 @@
+package com.thealgorithms.backtracking;
+
+/**
+ * Sudoku Solver using Backtracking Algorithm
+ * Solves a 9x9 Sudoku puzzle by filling empty cells with valid digits (1-9)
+ *
+ * @author Navadeep0007
+ */
+public final class SudokuSolver {
+
+    private static final int GRID_SIZE = 9;
+    private static final int SUBGRID_SIZE = 3;
+    private static final int EMPTY_CELL = 0;
+
+    private SudokuSolver() {
+        // Utility class, prevent instantiation
+    }
+
+    /**
+     * Solves the Sudoku puzzle using backtracking
+     *
+     * @param board 9x9 Sudoku board with 0 representing empty cells
+     * @return true if puzzle is solved, false otherwise
+     */
+    public static boolean solveSudoku(int[][] board) {
+        if (board == null || board.length != GRID_SIZE) {
+            return false;
+        }
+
+        for (int row = 0; row < GRID_SIZE; row++) {
+            if (board[row].length != GRID_SIZE) {
+                return false;
+            }
+        }
+
+        return solve(board);
+    }
+
+    /**
+     * Recursive helper method to solve the Sudoku puzzle
+     *
+     * @param board the Sudoku board
+     * @return true if solution is found, false otherwise
+     */
+    private static boolean solve(int[][] board) {
+        for (int row = 0; row < GRID_SIZE; row++) {
+            for (int col = 0; col < GRID_SIZE; col++) {
+                if (board[row][col] == EMPTY_CELL) {
+                    for (int number = 1; number <= GRID_SIZE; number++) {
+                        if (isValidPlacement(board, row, col, number)) {
+                            board[row][col] = number;
+
+                            if (solve(board)) {
+                                return true;
+                            }
+
+                            // Backtrack
+                            board[row][col] = EMPTY_CELL;
+                        }
+                    }
+                    return false;
+                }
+            }
+        }
+        return true;
+    }
+
+    /**
+     * Checks if placing a number at given position is valid
+     *
+     * @param board the Sudoku board
+     * @param row row index
+     * @param col column index
+     * @param number number to place (1-9)
+     * @return true if placement is valid, false otherwise
+     */
+    private static boolean isValidPlacement(int[][] board, int row, int col, int number) {
+        return !isNumberInRow(board, row, number) && !isNumberInColumn(board, col, number) && !isNumberInSubgrid(board, row, col, number);
+    }
+
+    /**
+     * Checks if number exists in the given row
+     *
+     * @param board the Sudoku board
+     * @param row row index
+     * @param number number to check
+     * @return true if number exists in row, false otherwise
+     */
+    private static boolean isNumberInRow(int[][] board, int row, int number) {
+        for (int col = 0; col < GRID_SIZE; col++) {
+            if (board[row][col] == number) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Checks if number exists in the given column
+     *
+     * @param board the Sudoku board
+     * @param col column index
+     * @param number number to check
+     * @return true if number exists in column, false otherwise
+     */
+    private static boolean isNumberInColumn(int[][] board, int col, int number) {
+        for (int row = 0; row < GRID_SIZE; row++) {
+            if (board[row][col] == number) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Checks if number exists in the 3x3 subgrid
+     *
+     * @param board the Sudoku board
+     * @param row row index
+     * @param col column index
+     * @param number number to check
+     * @return true if number exists in subgrid, false otherwise
+     */
+    private static boolean isNumberInSubgrid(int[][] board, int row, int col, int number) {
+        int subgridRowStart = row - row % SUBGRID_SIZE;
+        int subgridColStart = col - col % SUBGRID_SIZE;
+
+        for (int i = subgridRowStart; i < subgridRowStart + SUBGRID_SIZE; i++) {
+            for (int j = subgridColStart; j < subgridColStart + SUBGRID_SIZE; j++) {
+                if (board[i][j] == number) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Prints the Sudoku board
+     *
+     * @param board the Sudoku board
+     */
+    public static void printBoard(int[][] board) {
+        for (int row = 0; row < GRID_SIZE; row++) {
+            if (row % SUBGRID_SIZE == 0 && row != 0) {
+                System.out.println("-----------");
+            }
+            for (int col = 0; col < GRID_SIZE; col++) {
+                if (col % SUBGRID_SIZE == 0 && col != 0) {
+                    System.out.print("|");
+                }
+                System.out.print(board[row][col]);
+            }
+            System.out.println();
+        }
+    }
+}