solves #2319: Check if Matrix Is X-Matrix in java

Author: anishLearnsToCode

README.md

@@ -744,9 +744,9 @@
 | 2300 | [Successful Pairs of Spells and Potions](https://leetcode.com/problems/successful-pairs-of-spells-and-potions)                                                         |                                                                        [![Python](assets/python.png)](python/successfull_pairs_of_spells_and_potions.py)                                                                         |                                                                                                                                   |
 | 2303 | [Calculate Amount Paid in Taxes](https://leetcode.com/problems/calculate-amount-paid-in-taxes)                                                                         |                                                                                 [![Java](assets/java.png)](src/CalculateAmountPaidInTaxes.java)                                                                                  |                                                                                                                                   |
 | 2309 | [Greatest English Letter in Upper and Lower Case](https://leetcode.com/problems/greatest-english-letter-in-upper-and-lower-case)                                       |                                                                          [![Java](assets/java.png)](src/GreatestEnglishLetterInUpperAndLowerCase.java)                                                                           |                                                                                                                                   |
-| 2315 | [Count Asterisks](https://leetcode.com/problems/count-asterisks)                                                                                                       |                                                [![Java](assets/java.png)](src/CountAsterisks.java) [![Python](assets/python.png)](python/successfull_pairs_of_spells_and_potions.py)                                                 |                                                                                                                                   |
+| 2315 | [Count Asterisks](https://leetcode.com/problems/count-asterisks)                                                                                                       |                                              [![Java](assets/java.png)](src/CountAsterisks.java) [![Python](assets/python.png)](python/successfull_pairs_of_spells_and_potions.py)                                               |                                                                                                                                   |
 | 2316 | [Count Unreachable Pairs of Nodes in an Undirected Graph](https://leetcode.com/problems/count-unreachable-pairs-of-nodes-in-an-undirected-graph)                       |                                                                [![Python](assets/python.png)](python/count_unreachable_pair_of_node_in_an_undirectable_graph.py)                                                                 |                                                                                                                                   |
-| 2319 | [Check if Matrix Is X-Matrix](https://leetcode.com/problems/check-if-matrix-is-x-matrix)                                                                               |                                                                [![Python](assets/python.png)](python/count_unreachable_pair_of_node_in_an_undirectable_graph.py)                                                                 |                                                                                                                                   |
+| 2319 | [Check if Matrix Is X-Matrix](https://leetcode.com/problems/check-if-matrix-is-x-matrix)                                                                               |                                                                                       [![Java](assets/java.png)](src/CountAsterisks.java)                                                                                        |                                                                                                                                   |
 | 2325 | [Decode the Message](https://leetcode.com/problems/decode-the-message)                                                                                                 |                                                                [![Python](assets/python.png)](python/count_unreachable_pair_of_node_in_an_undirectable_graph.py)                                                                 |                                                                                                                                   |
 | 2331 | [Evaluate Boolean Binary Tree](https://leetcode.com/problems/evaluate-boolean-binary-tree)                                                                             |                                                                [![Python](assets/python.png)](python/count_unreachable_pair_of_node_in_an_undirectable_graph.py)                                                                 |                                                                                                                                   |
 | 2335 | [Minimum Amount of Time to Fill Cups](https://leetcode.com/problems/minimum-amount-of-time-to-fill-cups)                                                               |                                                                [![Python](assets/python.png)](python/count_unreachable_pair_of_node_in_an_undirectable_graph.py)                                                                 |                                                                                                                                   |

src/CheckIfMatrixIsXMatrix.java

@@ -0,0 +1,20 @@
+// https://leetcode.com/problems/check-if-matrix-is-x-matrix
+// T: O(n * n)
+// S: O(1)
+
+public class CheckIfMatrixIsXMatrix {
+    public boolean checkXMatrix(int[][] grid) {
+        for (int row = 0 ; row < grid.length ; row++) {
+            for (int column = 0 ; column < grid.length ; column++) {
+                if (isDiagonalCell(row, column, grid.length)) {
+                    if (grid[row][column] == 0) return false;
+                } else if (grid[row][column] != 0) return false;
+            }
+        }
+        return true;
+    }
+
+    private boolean isDiagonalCell(int row, int column, int length) {
+        return row == column || column == length - row - 1;
+    }
+}