fix(searches): add null safety and empty matrix handling to RowColumnWiseSorted2dArrayBinarySearch (#7725)

* fix(searches): add null safety and empty matrix handling to RowColumnWiseSorted2dArrayBinarySearch

* refactor(searches): scope validation to rectangular matrices per review

Author: hardikkaurani

src/main/java/com/thealgorithms/searches/RowColumnWiseSorted2dArrayBinarySearch.java

@@ -20,14 +20,18 @@
  * doesn't exist in the array, an array
  * {-1, -1} will be returned.
  */
-public class RowColumnWiseSorted2dArrayBinarySearch implements MatrixSearchAlgorithm {
+public final class RowColumnWiseSorted2dArrayBinarySearch implements MatrixSearchAlgorithm {
 
     @Override
     public <T extends Comparable<T>> int[] find(T[][] matrix, T key) {
         return search(matrix, key);
     }
 
     public static <T extends Comparable<T>> int[] search(T[][] matrix, T target) {
+        if (matrix == null || matrix.length == 0 || matrix[0] == null || matrix[0].length == 0 || target == null) {
+            return new int[] {-1, -1};
+        }
+
         int rowPointer = 0; // The pointer at 0th row
         int colPointer = matrix[0].length - 1; // The pointer at end column
 

src/test/java/com/thealgorithms/searches/RowColumnWiseSorted2dArrayBinarySearchTest.java

@@ -237,4 +237,56 @@ public void rowColumnSorted2dArrayBinarySearchTestTallMatrixNotFound() {
         assertEquals(expected[0], ans[0]);
         assertEquals(expected[1], ans[1]);
     }
+
+    @Test
+    public void testNullMatrixReturnsNotFound() {
+        int[] ans = RowColumnWiseSorted2dArrayBinarySearch.search(null, 5);
+        int[] expected = {-1, -1};
+        assertEquals(expected[0], ans[0]);
+        assertEquals(expected[1], ans[1]);
+    }
+
+    @Test
+    public void testEmptyMatrixReturnsNotFound() {
+        Integer[][] matrix = {};
+        int[] ans = RowColumnWiseSorted2dArrayBinarySearch.search(matrix, 5);
+        int[] expected = {-1, -1};
+        assertEquals(expected[0], ans[0]);
+        assertEquals(expected[1], ans[1]);
+    }
+
+    @Test
+    public void testEmptyFirstRowReturnsNotFound() {
+        Integer[][] matrix = {{}};
+        int[] ans = RowColumnWiseSorted2dArrayBinarySearch.search(matrix, 5);
+        int[] expected = {-1, -1};
+        assertEquals(expected[0], ans[0]);
+        assertEquals(expected[1], ans[1]);
+    }
+
+    @Test
+    public void testNullTargetReturnsNotFound() {
+        int[] ans = RowColumnWiseSorted2dArrayBinarySearch.search(WIDE_RECTANGULAR_MATRIX, null);
+        int[] expected = {-1, -1};
+        assertEquals(expected[0], ans[0]);
+        assertEquals(expected[1], ans[1]);
+    }
+
+    @Test
+    public void testNullFirstRowReturnsNotFound() {
+        Integer[][] matrix = {null};
+        int[] ans = RowColumnWiseSorted2dArrayBinarySearch.search(matrix, 5);
+        int[] expected = {-1, -1};
+        assertEquals(expected[0], ans[0]);
+        assertEquals(expected[1], ans[1]);
+    }
+
+    @Test
+    public void testFindMethodThroughInterface() {
+        RowColumnWiseSorted2dArrayBinarySearch searcher = new RowColumnWiseSorted2dArrayBinarySearch();
+        int[] ans = searcher.find(WIDE_RECTANGULAR_MATRIX, 35);
+        int[] expected = {1, 2};
+        assertEquals(expected[0], ans[0]);
+        assertEquals(expected[1], ans[1]);
+    }
 }