leetcode766

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Description

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

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

Idea

直接遍历，不过是要check遍历元素和斜对的元素是不是一样

Code

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class Solution(object):
    def isToeplitzMatrix(self, matrix):
        """
        :type matrix: List[List[int]]
        :rtype: bool
        """
        if not matrix or len(matrix) == 0:
            return False
        
        rows = len(matrix)
        cols = len(matrix[0])
        
        for r in range(rows):
            for c in range(cols):
                if (r + 1 <= rows -1 and c + 1 <= cols - 1) and matrix[r][c] != matrix[r + 1][c + 1]:
                    return False
        
        return True