[leetcode-766-Toeplitz Matrix]

Posted 2020-10-22 hellowOOOrld

leetcode-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].

 思路：

遍历即可，看是否与左上角元素相同。

bool isToeplitzMatrix(vector<vector<int>>& matrix)
 {
    int m  = matrix.size(), n = matrix[0].size();
    for(int i=1;i<m;i++)
    {
        for(int j = 1;j<n;j++)
        {
            if(matrix[i][j] != matrix[i-1][j-1])return false;
        }
    }    
    return true;
 }