add 2319

Author: fishercoder1534

README.md

@@ -8,6 +8,7 @@ _If you like this project, please leave me a star._ ★
 
 | #    |      Title     | Solutions                                                                                                                                | Video                                                                         | Difficulty  | Tag                  
 |------|----------------|------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------|-------------|-------------
+| 2319 |[Check if Matrix Is X-Matrix](https://leetcode.com/problems/check-if-matrix-is-x-matrix/)| [Java](../master/src/main/java/com/fishercoder/solutions/_2319.java)                                                                     || Easy                                                                             ||
 | 2315 |[Count Asterisks](https://leetcode.com/problems/count-asterisks/)| [Java](../master/src/main/java/com/fishercoder/solutions/_2315.java)                                                                     || Easy                                                                             ||
 | 2309 |[Greatest English Letter in Upper and Lower Case](https://leetcode.com/problems/greatest-english-letter-in-upper-and-lower-case/)| [Java](../master/src/main/java/com/fishercoder/solutions/_2309.java)                                                                     || Easy                                                                             ||
 | 2303 |[Calculate Amount Paid in Taxes](https://leetcode.com/problems/calculate-amount-paid-in-taxes/)| [Java](../master/src/main/java/com/fishercoder/solutions/_2303.java)                                                                     || Easy                                                                             ||

src/main/java/com/fishercoder/solutions/_2319.java

@@ -0,0 +1,32 @@
+package com.fishercoder.solutions;
+
+public class _2319 {
+    public static class Solution1 {
+        public boolean checkXMatrix(int[][] grid) {
+            int m = grid.length;
+            boolean[][] checked = new boolean[m][m];
+            for (int i = 0; i < m; i++) {
+                if (grid[i][i] == 0) {
+                    return false;
+                } else {
+                    checked[i][i] = true;
+                }
+            }
+            for (int i = 0, j = m - 1; i < m && j >= 0; i++, j--) {
+                if (grid[i][j] == 0) {
+                    return false;
+                } else {
+                    checked[i][j] = true;
+                }
+            }
+            for (int i = 0; i < m; i++) {
+                for (int j = 0; j < m; j++) {
+                    if (!checked[i][j] && grid[i][j] != 0) {
+                        return false;
+                    }
+                }
+            }
+            return true;
+        }
+    }
+}