[LeetCode] Challenge log 766

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766. Toeplitz Matrix

Skip the first row and first column and traverse the matrix, check if m[i][j] = m[i-1][j-1].

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:

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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:

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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].
Soulution:
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class Solution:
    def isToeplitzMatrix(self, matrix):
        """
        :type matrix: List[List[int]]
        :rtype: bool
        """
        nrow = len(matrix)
        ncol = len(matrix[0])
        
        for i in range(1, nrow):
            for j in range(1, ncol):
                if matrix[i-1][j-1] != matrix[i][j]:
                    return False
        return True
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