0.题目

1. 动态规划 O(mn) O(mn)

class Solution:
    def minPathSum(self, grid):
        dp = [grid[_] for _ in range(len(grid))] #复制grid
        for i in range(len(grid)):
            for j in range(len(grid[0])):
                if i>=1 and j>=1:
                    dp[i][j] = min(dp[i-1][j],dp[i][j-1])+grid[i][j]
                elif i>=1:
                    dp[i][j] = dp[i-1][j]+grid[i][j]
                elif j>=1:
                    dp[i][j] = dp[i][j-1]+grid[i][j]
                else:
                    continue
        return dp[-1][-1]