2319

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

Related Topics:
Array, Matrix

Similar Questions:

• Matrix Diagonal Sum (Easy)

Solution 1.

// OJ: https://leetcode.com/problems/check-if-matrix-is-x-matrix
// Author: github.com/lzl124631x
// Time: O(N^2)
// Space: O(1)
class Solution {
public:
    bool checkXMatrix(vector<vector<int>>& A) {
        int N = A.size();
        for (int i = 0; i < N; ++i) {
            for (int j = 0; j < N; ++j) {
                if (i == j || j == N - i - 1) {
                    if (A[i][j] == 0) return false;
                } else if (A[i][j] != 0) return false;
            }
        }
        return true;
    }
};