766. Toeplitz Matrix

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].

解题思路:

　　多重循环比较，感觉没有什么难点，不知道有没有更简单的方法。

class Solution {
public:
    bool isToeplitzMatrix(vector<vector<int>>& matrix) {
        int row = matrix.size();
        int column = matrix[0].size();

        for (int i = 0; i < row; i++) {
            for (int j = 0; j < column; j++) {
                for (int m = i + 1, n = j + 1; m < row && n < column; m++, n++) {
                    if (matrix[i][j] != matrix[m][n]) {
                        return false;
                    }
                }
            }
        }

        return true;
    }
};