fix(searches): fix boundary safety and null checks in SaddlebackSearch

Author: hardikkaurani

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

@@ -19,24 +19,39 @@ private SaddlebackSearch() {
     }
 
     /**
-     * This method performs Saddleback Search
+     * Searches for a key in a row-wise and column-wise sorted 2D array starting from the bottom-left corner.
+     *
+     * @param arr The sorted matrix.
+     * @param key The element to search for.
+     * @throws IllegalArgumentException if the array is null or empty.
+     * @return The index (row and column) of the element if found. Else returns {-1, -1}.
+     */
+    public static int[] find(int[][] arr, int key) {
+        if (arr == null || arr.length == 0) {
+            throw new IllegalArgumentException("Array is empty");
+        }
+        return find(arr, arr.length - 1, 0, key);
+    }
+
+    /**
+     * This method performs Saddleback Search starting from the specified row and column.
      *
      * @param arr The **Sorted** array in which we will search the element.
      * @param row the current row.
      * @param col the current column.
      * @param key the element that we want to search for.
-     * @throws IllegalArgumentException if the array is empty.
+     * @throws IllegalArgumentException if the array is null or empty.
      * @return The index(row and column) of the element if found. Else returns
      * -1 -1.
      */
-    static int[] find(int[][] arr, int row, int col, int key) {
-        if (arr.length == 0) {
+    public static int[] find(int[][] arr, int row, int col, int key) {
+        if (arr == null || arr.length == 0) {
             throw new IllegalArgumentException("Array is empty");
         }
 
         // array to store the answer row and column
         int[] ans = {-1, -1};
-        if (row < 0 || col >= arr[row].length) {
+        if (row < 0 || row >= arr.length || arr[row] == null || col < 0 || col >= arr[row].length) {
             return ans;
         }
         if (arr[row][col] == key) {

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

@@ -82,4 +82,53 @@ void testFindSingleElementNotExists() {
         int[] result = SaddlebackSearch.find(arr, 0, 0, 10);
         assertArrayEquals(new int[] {-1, -1}, result, "Element 10 should not be found in single element array");
     }
+
+    /**
+     * Test convenience method searching from the bottom-left corner automatically.
+     */
+    @Test
+    void testFindWithConvenienceMethod() {
+        int[][] arr = {{-10, -5, -3, 4, 9}, {-6, -2, 0, 5, 10}, {-4, -1, 1, 6, 12}, {2, 3, 7, 8, 13}, {100, 120, 130, 140, 150}};
+        int[] result = SaddlebackSearch.find(arr, 4);
+        assertArrayEquals(new int[] {0, 3}, result, "Element 4 should be found at (0, 3) using convenience overload");
+    }
+
+    /**
+     * Test searching in a null array throws IllegalArgumentException.
+     */
+    @Test
+    void testFindWithNullArray() {
+        assertThrows(IllegalArgumentException.class, () -> SaddlebackSearch.find(null, 4));
+        assertThrows(IllegalArgumentException.class, () -> SaddlebackSearch.find(null, 0, 0, 4));
+    }
+
+    /**
+     * Test row index out of bounds returns {-1, -1}.
+     */
+    @Test
+    void testFindWithRowOutOfBounds() {
+        int[][] arr = {{1, 2}, {3, 4}};
+        int[] result = SaddlebackSearch.find(arr, 5, 0, 3);
+        assertArrayEquals(new int[] {-1, -1}, result, "Row index out of bounds should return {-1, -1}");
+    }
+
+    /**
+     * Test negative column index returns {-1, -1}.
+     */
+    @Test
+    void testFindWithNegativeColumn() {
+        int[][] arr = {{1, 2}, {3, 4}};
+        int[] result = SaddlebackSearch.find(arr, 1, -1, 3);
+        assertArrayEquals(new int[] {-1, -1}, result, "Negative column index should return {-1, -1}");
+    }
+
+    /**
+     * Test null row in matrix returns {-1, -1} safely.
+     */
+    @Test
+    void testFindWithNullRowInMatrix() {
+        int[][] arr = {{1, 2}, null, {5, 6}};
+        int[] result = SaddlebackSearch.find(arr, 1, 0, 5);
+        assertArrayEquals(new int[] {-1, -1}, result, "Null row in matrix should safely return {-1, -1}");
+    }
 }