Correct column pointer initialization in RowColumnWiseSorted2dArrayBinarySearch (#6333)

Author: codingmydna

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

@@ -29,7 +29,7 @@ public <T extends Comparable<T>> int[] find(T[][] matrix, T key) {
 
     public static <T extends Comparable<T>> int[] search(T[][] matrix, T target) {
         int rowPointer = 0; // The pointer at 0th row
-        int colPointer = matrix.length - 1; // The pointer at end column
+        int colPointer = matrix[0].length - 1; // The pointer at end column
 
         while (rowPointer < matrix.length && colPointer >= 0) {
             int comp = target.compareTo(matrix[rowPointer][colPointer]);

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

@@ -110,4 +110,131 @@ public void rowColumnSorted2dArrayBinarySearchTestNotFound() {
         assertEquals(expected[0], ans[0]);
         assertEquals(expected[1], ans[1]);
     }
+
+    /**
+     * Tests for a WIDE rectangular matrix (3 rows, 4 columns)
+     */
+    private static final Integer[][] WIDE_RECTANGULAR_MATRIX = {
+        {10, 20, 30, 40},
+        {15, 25, 35, 45},
+        {18, 28, 38, 48},
+    };
+
+    @Test
+    public void rowColumnSorted2dArrayBinarySearchTestWideMatrixMiddle() {
+        Integer target = 25; // A value in the middle
+        int[] ans = RowColumnWiseSorted2dArrayBinarySearch.search(WIDE_RECTANGULAR_MATRIX, target);
+        int[] expected = {1, 1};
+        assertEquals(expected[0], ans[0]);
+        assertEquals(expected[1], ans[1]);
+    }
+
+    @Test
+    public void rowColumnSorted2dArrayBinarySearchTestWideMatrixTopRightCorner() {
+        Integer target = 40; // The top-right corner element
+        int[] ans = RowColumnWiseSorted2dArrayBinarySearch.search(WIDE_RECTANGULAR_MATRIX, target);
+        int[] expected = {0, 3};
+        assertEquals(expected[0], ans[0]);
+        assertEquals(expected[1], ans[1]);
+    }
+
+    @Test
+    public void rowColumnSorted2dArrayBinarySearchTestWideMatrixBottomLeftCorner() {
+        Integer target = 18; // The bottom-left corner element
+        int[] ans = RowColumnWiseSorted2dArrayBinarySearch.search(WIDE_RECTANGULAR_MATRIX, target);
+        int[] expected = {2, 0};
+        assertEquals(expected[0], ans[0]);
+        assertEquals(expected[1], ans[1]);
+    }
+
+    @Test
+    public void rowColumnSorted2dArrayBinarySearchTestWideMatrixTopLeftCorner() {
+        Integer target = 10; // The top-left corner element
+        int[] ans = RowColumnWiseSorted2dArrayBinarySearch.search(WIDE_RECTANGULAR_MATRIX, target);
+        int[] expected = {0, 0};
+        assertEquals(expected[0], ans[0]);
+        assertEquals(expected[1], ans[1]);
+    }
+
+    @Test
+    public void rowColumnSorted2dArrayBinarySearchTestWideMatrixBottomRightCorner() {
+        Integer target = 48; // The bottom-right corner element
+        int[] ans = RowColumnWiseSorted2dArrayBinarySearch.search(WIDE_RECTANGULAR_MATRIX, target);
+        int[] expected = {2, 3};
+        assertEquals(expected[0], ans[0]);
+        assertEquals(expected[1], ans[1]);
+    }
+
+    @Test
+    public void rowColumnSorted2dArrayBinarySearchTestWideMatrixNotFound() {
+        Integer target = 99; // A value that does not exist
+        int[] ans = RowColumnWiseSorted2dArrayBinarySearch.search(WIDE_RECTANGULAR_MATRIX, target);
+        int[] expected = {-1, -1};
+        assertEquals(expected[0], ans[0]);
+        assertEquals(expected[1], ans[1]);
+    }
+
+    /**
+     * Tests for a TALL rectangular matrix (4 rows, 3 columns)
+     */
+    private static final Integer[][] TALL_RECTANGULAR_MATRIX = {
+        {10, 20, 30},
+        {15, 25, 35},
+        {18, 28, 38},
+        {21, 31, 41},
+    };
+
+    @Test
+    public void rowColumnSorted2dArrayBinarySearchTestTallMatrixMiddle() {
+        Integer target = 28; // A value in the middle
+        int[] ans = RowColumnWiseSorted2dArrayBinarySearch.search(TALL_RECTANGULAR_MATRIX, target);
+        int[] expected = {2, 1};
+        assertEquals(expected[0], ans[0]);
+        assertEquals(expected[1], ans[1]);
+    }
+
+    @Test
+    public void rowColumnSorted2dArrayBinarySearchTestTallMatrixTopRightCorner() {
+        Integer target = 30; // The top-right corner element
+        int[] ans = RowColumnWiseSorted2dArrayBinarySearch.search(TALL_RECTANGULAR_MATRIX, target);
+        int[] expected = {0, 2};
+        assertEquals(expected[0], ans[0]);
+        assertEquals(expected[1], ans[1]);
+    }
+
+    @Test
+    public void rowColumnSorted2dArrayBinarySearchTestTallMatrixBottomLeftCorner() {
+        Integer target = 21; // The bottom-left corner element
+        int[] ans = RowColumnWiseSorted2dArrayBinarySearch.search(TALL_RECTANGULAR_MATRIX, target);
+        int[] expected = {3, 0};
+        assertEquals(expected[0], ans[0]);
+        assertEquals(expected[1], ans[1]);
+    }
+
+    @Test
+    public void rowColumnSorted2dArrayBinarySearchTestTallMatrixTopLeftCorner() {
+        Integer target = 10; // The top-left corner element
+        int[] ans = RowColumnWiseSorted2dArrayBinarySearch.search(TALL_RECTANGULAR_MATRIX, target);
+        int[] expected = {0, 0};
+        assertEquals(expected[0], ans[0]);
+        assertEquals(expected[1], ans[1]);
+    }
+
+    @Test
+    public void rowColumnSorted2dArrayBinarySearchTestTallMatrixBottomRightCorner() {
+        Integer target = 41; // The bottom-right corner element
+        int[] ans = RowColumnWiseSorted2dArrayBinarySearch.search(TALL_RECTANGULAR_MATRIX, target);
+        int[] expected = {3, 2};
+        assertEquals(expected[0], ans[0]);
+        assertEquals(expected[1], ans[1]);
+    }
+
+    @Test
+    public void rowColumnSorted2dArrayBinarySearchTestTallMatrixNotFound() {
+        Integer target = 5; // A value that does not exist
+        int[] ans = RowColumnWiseSorted2dArrayBinarySearch.search(TALL_RECTANGULAR_MATRIX, target);
+        int[] expected = {-1, -1};
+        assertEquals(expected[0], ans[0]);
+        assertEquals(expected[1], ans[1]);
+    }
 }