2319. Check if Matrix Is X-Matrix

Difficulty:
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Problem

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

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:

Solution (Java)

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;
    }
}

Explain:

nope.

Complexity: