fix(searches): support rectangular matrices and null safety in SearchInARowAndColWiseSortedMatrix (#7655)

* fix(searches): support rectangular matrices and null safety in SearchInARowAndColWiseSortedMatrix

* style: format SearchInARowAndColWiseSortedMatrixTest with clang-format

Author: hardikkaurani

src/main/java/com/thealgorithms/searches/SearchInARowAndColWiseSortedMatrix.java

@@ -1,32 +1,42 @@
-package com.thealgorithms.searches;
-
-public class SearchInARowAndColWiseSortedMatrix {
-    /**
-     * Search a key in row and column wise sorted matrix
-     *
-     * @param matrix matrix to be searched
-     * @param value  Key being searched for
-     * @author Sadiul Hakim : https://github.com/sadiul-hakim
-     */
-    public int[] search(int[][] matrix, int value) {
-        int n = matrix.length;
-        // This variable iterates over rows
-        int i = 0;
-        // This variable iterates over columns
-        int j = n - 1;
-        int[] result = {-1, -1};
-        while (i < n && j >= 0) {
-            if (matrix[i][j] == value) {
-                result[0] = i;
-                result[1] = j;
-                return result;
-            }
-            if (value > matrix[i][j]) {
-                i++;
-            } else {
-                j--;
-            }
-        }
-        return result;
-    }
-}
+package com.thealgorithms.searches;
+
+public final class SearchInARowAndColWiseSortedMatrix {
+    /**
+     * Search a key in row and column wise sorted matrix
+     *
+     * @param matrix matrix to be searched
+     * @param value  Key being searched for
+     * @return row and column indices if found, otherwise {-1, -1}
+     * @author Sadiul Hakim : https://github.com/sadiul-hakim
+     */
+    public int[] search(int[][] matrix, int value) {
+        if (matrix == null || matrix.length == 0 || matrix[0] == null || matrix[0].length == 0) {
+            return new int[] {-1, -1};
+        }
+
+        int rows = matrix.length;
+        int cols = matrix[0].length;
+        // This variable iterates over rows
+        int i = 0;
+        // This variable iterates over columns, starting from top-right corner
+        int j = cols - 1;
+        int[] result = {-1, -1};
+        while (i < rows && j >= 0) {
+            if (matrix[i] == null || j >= matrix[i].length) {
+                i++;
+                continue;
+            }
+            if (matrix[i][j] == value) {
+                result[0] = i;
+                result[1] = j;
+                return result;
+            }
+            if (value > matrix[i][j]) {
+                i++;
+            } else {
+                j--;
+            }
+        }
+        return result;
+    }
+}

src/test/java/com/thealgorithms/searches/SearchInARowAndColWiseSortedMatrixTest.java

@@ -63,4 +63,36 @@ void testSearchInColWiseSortedMatrix() {
         int[] expected = {1, 1}; // Found at (1, 1)
         assertArrayEquals(expected, searcher.search(matrix, value), "Value should be found in the column-wise sorted matrix");
     }
+
+    @Test
+    void testSearchInNullMatrix() {
+        assertArrayEquals(new int[] {-1, -1}, searcher.search(null, 5), "Should return {-1, -1} for null matrix");
+    }
+
+    @Test
+    void testSearchInMatrixWithEmptyRows() {
+        int[][] matrix = {{}};
+        assertArrayEquals(new int[] {-1, -1}, searcher.search(matrix, 5), "Should return {-1, -1} for matrix with empty first row");
+    }
+
+    @Test
+    void testSearchInRectangularMatrixMoreColsThanRowsFound() {
+        int[][] matrix = {{1, 3, 5, 7, 9}, {2, 4, 6, 8, 10}};
+        int[] expected = {0, 4}; // Value 9 is at row 0, col 4
+        assertArrayEquals(expected, searcher.search(matrix, 9), "Value 9 should be found at row 0, col 4");
+    }
+
+    @Test
+    void testSearchInRectangularMatrixMoreRowsThanColsFound() {
+        int[][] matrix = {{1, 5}, {2, 6}, {3, 7}, {4, 8}};
+        int[] expected = {2, 0}; // Value 3 is at row 2, col 0
+        assertArrayEquals(expected, searcher.search(matrix, 3), "Value 3 should be found at row 2, col 0");
+    }
+
+    @Test
+    void testSearchInRectangularMatrixNotFound() {
+        int[][] matrix = {{1, 3, 5}, {2, 4, 6}, {7, 8, 9}, {10, 11, 12}};
+        int[] expected = {-1, -1};
+        assertArrayEquals(expected, searcher.search(matrix, 15), "Value 15 should not be found");
+    }
 }