LeetCode 931. Minimum Falling Path Sum解题报告(python)_leetcode931python版本实现

931. Minimum Falling Path Sum

931. Minimum Falling Path Sum python solution

题目描述

Given a square array of integers A, we want the minimum sum of a falling path through A.
A falling path starts at any element in the first row, and chooses one element from each row. The next row’s choice must be in a column that is different from the previous row’s column by at most one.

解析

解题思路比较简单，一层层计算下来即可，见代码。

// An highlighted block
class Solution:
    def minFallingPathSum(self, A):
        """
        :type A: List[List[int]]
        :rtype: int
        """
        for i in range(1, len(A)):
            for j in range(len(A[0])):
                if j-1>=0:
                    topleft=A[i-1][j-1]
                else:
                    topleft=float('inf')
                if j+1<len(A[0]):
                    topright=A[i-1][j+1]
                else:
                    topright=float('inf')
                A[i][j] += min(topleft, topright, A[i-1][j])
        return min(A[-1])       
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Reference

https://leetcode.com/problems/minimum-falling-path-sum/discuss/221123/Very-Easy-to-Understand-Python-6-line-DP-with-no-extra-space-beats-90