描述
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:
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.
Example 2:
Input:
matrix = [
[1,2],
[2,2]
]
Output: False
Explanation:
The diagonal "[1, 2]" has different elements.
Note:
matrix will be a 2D array of integers.
matrix will have a number of rows and columns in range [1, 20].
matrix[i][j] will be integers in range [0, 99].
解析
根据题意只要判断从矩阵的左上角到右下角都是相同的数字的即可。时间复杂度为 O(M*N),空间复杂度为 O(1)。
解答
class Solution(object):
def isToeplitzMatrix(self, matrix):
"""
:type matrix: List[List[int]]
:rtype: bool
"""
return all(r==0 or c==0 or matrix[r-1][c-1]==val for r,row in enumerate(matrix) for c,val in enumerate(row))
运行结果
Runtime: 72 ms, faster than 73.33% of Python online submissions for Toeplitz Matrix.
Memory Usage: 11.8 MB, less than 17.84% of Python online submissions for Toeplitz Matrix.
