Leetcode64 最小路径和[DP]

题目描述

解法

class Solution:
    def minPathSum(self, grid: List[List[int]]) -> int:
        m = len(grid)
        if not m:
            return NULL
        n = len(grid[0])
        dp = [[0]*n for i in range(m)]
        dp[0][0] = grid[0][0]
        for i in range(1,n):
            dp[0][i] = dp[0][i-1] + grid[0][i]
        for i in range(1,m):
            dp[i][0] = dp[i-1][0] + grid[i][0]
        for i in range(1,m):
            for j in range(1,n):
                dp[i][j] = min(dp[i-1][j],dp[i][j-1]) + grid[i][j]
        return dp[m-1][n-1]

 

Note

• 可以降维优化