LeetCode-in-Java

2319. Check if Matrix Is X-Matrix

Easy

A square matrix is said to be an X-Matrix if both of the following conditions hold:

1. All the elements in the diagonals of the matrix are non-zero.
2. All other elements are 0.

Given a 2D integer array grid of size n x n representing a square matrix, return true if grid is an X-Matrix. Otherwise, return false.

Example 1:

Input: grid = [[2,0,0,1],[0,3,1,0],[0,5,2,0],[4,0,0,2]]

Output: true

Explanation: Refer to the diagram above.

An X-Matrix should have the green elements (diagonals) be non-zero and the red elements be 0.

Thus, grid is an X-Matrix.

Example 2:

Input: grid = [[5,7,0],[0,3,1],[0,5,0]]

Output: false

Explanation: Refer to the diagram above.

An X-Matrix should have the green elements (diagonals) be non-zero and the red elements be 0.

Thus, grid is not an X-Matrix.

Constraints:

• n == grid.length == grid[i].length
• 3 <= n <= 100
• 0 <= grid[i][j] <= 105

Solution

public class Solution {
    public boolean checkXMatrix(int[][] grid) {
        for (int i = 0; i < grid.length; i++) {
            for (int j = 0; j < grid[0].length; j++) {
                if (i == j || i + j == grid.length - 1) {
                    if (grid[i][j] == 0) {
                        return false;
                    }
                } else {
                    if (grid[i][j] != 0) {
                        return false;
                    }
                }
            }
        }
        return true;
    }
}

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