A matrix is Toeplitz if every diagonal from top-left to bottom-right has the same element.

Now given an M x N matrix, return True if and only if the matrix is Toeplitz.

Example 1:

Input: matrix = [[1,2,3,4],[5,1,2,3],[9,5,1,2]]
Output: True
Explanation:
1234
5123
9512

In the above grid, the diagonals are "[9]", "[5, 5]", "[1, 1, 1]", "[2, 2, 2]", "[3, 3]", "[4]", and in each diagonal all elements are the same, so the answer is True.

Example 2:

Input: matrix = [[1,2],[2,2]]
Output: False
Explanation:
The diagonal "[1, 2]" has different elements.

Note:

1. matrix will be a 2D array of integers.
2. matrix will have a number of rows and columns in range [1, 20].
3. matrix[i][j] will be integers in range [0, 99].

左上到右下的一條斜線上的數要相同，才能稱為這個xxx矩陣。

class Solution {
public:
    bool isToeplitzMatrix(vector<vector<int>>& matrix) {
        
        int row = matrix.size(), col = matrix[0].size();
        
        for(int i = 1; i != row; ++i)
        {
            for(int j = 1; j != col; ++j)
            {
                if(matrix[i][j] != matrix[i-1
 
][j-1])//第一行第一列不用管
                    return false;  
            }
        }
        return true;  
    }
};

我看discuss裏很多這種解法，比較大眾思維吧~~

Toeplitz Matrix——leetcode