Added a new Feature called Sudoku Solver by using Backtracking and Re…

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

@@ -0,0 +1,99 @@
+package com.thealgorithms.backtracking;
+
+/**
+ * Solves a Sudoku of any level and prints solved Sudoku
+ * @author Indraneela Doradla (<a href="https://github.com/captiosus1">git-Indraneela Doradla</a>)
+ */
+public final class SudokuSolver {
+
+    private SudokuSolver() {
+        // Private constructor to prevent instantiation
+    }
+
+    /**
+     * Solves the Sudoku using backtracking
+     * @param board the Sudoku grid
+     * @return boolean indicating if the Sudoku can be solved
+     */
+    public static boolean solveSudoku(int[][] board) {
+        int r = -1, c = -1;
+        boolean isEmpty = true;
+
+        // Finding the first empty position
+        for (int i = 0; i < board.length; i++) {
+            for (int j = 0; j < board[0].length; j++) {
+                if (board[i][j] == 0) {
+                    r = i;
+                    c = j;
+                    isEmpty = false;
+                    break;
+                }
+            }
+            if (!isEmpty) break;
+        }
+
+        // If no empty position is found, the Sudoku is solved
+        if (isEmpty) {
+            return true;
+        }
+
+        // Try filling the empty position with numbers from 1 to 9
+        for (int num = 1; num <= 9; num++) {
+            if (isSafe(board, r, c, num)) {
+                board[r][c] = num;
+                if (solveSudoku(board)) {
+                    return true; // Successfully solved
+                }
+                board[r][c] = 0; // Backtrack
+            }
+        }
+
+        return false; // No solution found, backtrack
+    }
+
+    /**
+     * Checks if placing a number at the given position is valid
+     * @param board the Sudoku grid
+     * @param r row index
+     * @param c column index
+     * @param val the value to place
+     * @return boolean indicating if it's safe to place the value
+     */
+    public static boolean isSafe(int[][] board, int r, int c, int val) {
+        // Check the row and column
+        for (int i = 0; i < board.length; i++) {
+            if (board[i][c] == val || board[r][i] == val) {
+                return false;
+            }
+        }
+
+        // Check the 3x3 subgrid
+        int sqrt = (int) Math.sqrt(board.length);
+        int boxRowStart = r - r % sqrt;
+        int boxColStart = c - c % sqrt;
+
+        for (int i = boxRowStart; i < boxRowStart + sqrt; i++) {
+            for (int j = boxColStart; j < boxColStart + sqrt; j++) {
+                if (board[i][j] == val) {
+                    return false;
+                }
+            }
+        }
+
+        return true;
+    }
+
+    /**
+     * Prints the Sudoku grid
+     * @param board the Sudoku grid
+     */
+    public static void printSudoku(int[][] board) {
+        for (int[] row : board) {
+            for (int num : row) {
+                System.out.print(num + " ");
+            }
+            System.out.println();
+        }
+        System.out.println();
+    }
+}