[LeetCode]#766. Toeplitz Matrix

Environment: Python 3.8

Key technique: for

Given an m x n matrix, return true if the matrix is Toeplitz. Otherwise, return false.

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

Example 1:

Input: matrix = [[1,2,3,4],[5,1,2,3],[9,5,1,2]]
Output: true
Explanation:
In the above grid, the diagonals are:
"[9]", "[5, 5]", "[1, 1, 1]", "[2, 2, 2]", "[3, 3]", "[4]".
In each diagonal all elements are the same, so the answer is True.

Analysis:

1. There is no need to check matrix[2][0] and matrix[0][3]
2. Check matrix[i-1][j-1] is equal matrix[i][j] or not.
3. If is equal, reture True, else return False.

Solution:

class Solution:
    def isToeplitzMatrix(self, matrix):
        for i in range(1,len(matrix)):
            for j in range(1, len(matrix[0])):
                if matrix[i-1][j-1]!=matrix[i][j]:
                    return False
        return True

Submissions:

Reference:

https://leetcode.com/problems/toeplitz-matrix/discuss/1045481/Easy-python-solution