LeetCode刷题DAY 36：最小路径和

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