add search 2D matrix solutions for both LeetCode variations

Author: MohakAgrawal25

src/main/java/com/thealgorithms/matrix/Search2DMatrix.java

@@ -0,0 +1,87 @@
+package com.thealgorithms.matrix;
+
+/**
+ * Two variations of searching in a 2D matrix
+ * 
+ * Variation 1:
+ * - Each row is sorted left to right
+ * - Each column is sorted top to bottom
+ * 
+ * Variation 2:
+ * - The matrix is a flattened sorted array
+ * - i.e., row 0 ends, row 1 continues (matrix is sorted as a 1D array)
+ * 
+ * LeetCode: #74 and #240
+ */
+public class Search2DMatrix {
+
+    /**
+     * Variation 1: Search in a matrix where each row and each column is sorted
+     * Time: O(m + n)
+     *
+     * @param matrix input matrix
+     * @param target value to find
+     * @return true if found, false otherwise
+     */
+    public static boolean searchMatrixSortedRowsAndCols(int[][] matrix, int target) {
+        int rows = matrix.length;
+        if (rows == 0) return false;
+
+        int cols = matrix[0].length;
+        int row = 0, col = cols - 1;
+
+        while (row < rows && col >= 0) {
+            int val = matrix[row][col];
+            if (val == target) return true;
+            else if (val > target) col--;
+            else row++;
+        }
+
+        return false;
+    }
+
+    /**
+     * Variation 2: Search in a matrix that behaves like a flattened sorted array
+     * Time: O(log(m * n))
+     *
+     * @param matrix input matrix
+     * @param target value to find
+     * @return true if found, false otherwise
+     */
+    public static boolean searchMatrixFlattenedSorted(int[][] matrix, int target) {
+        int rows = matrix.length;
+        if (rows == 0) return false;
+
+        int cols = matrix[0].length;
+        int left = 0, right = rows * cols - 1;
+
+        while (left <= right) {
+            int mid = left + (right - left) / 2;
+            int val = matrix[mid / cols][mid % cols];
+
+            if (val == target) return true;
+            else if (val < target) left = mid + 1;
+            else right = mid - 1;
+        }
+
+        return false;
+    }
+
+    // Example usage
+    public static void main(String[] args) {
+        int[][] matrix1 = {
+            {1, 4, 7, 11},
+            {2, 5, 8, 12},
+            {3, 6, 9, 16},
+            {10, 13, 14, 17}
+        };
+        System.out.println(searchMatrixSortedRowsAndCols(matrix1, 5));  // true
+
+        int[][] matrix2 = {
+            {1, 3, 5, 7},
+            {10, 11, 16, 20},
+            {23, 30, 34, 50}
+        };
+        System.out.println(searchMatrixFlattenedSorted(matrix2, 3));   // true
+    }
+}