Leetcode: Minimum Path Sum @Python

class Solution:
    # @param grid, a list of lists of integers
    # @return an integer
    def minPathSum(self, grid):
        row=len(grid)
        col=len(grid[0])
        if row*col==0:
            return 0
        dp=[[grid[j][i] for i in range(col)] for j in range(row)]
        for i in range(1,row):
            dp[i][0]=dp[i-1][0]+grid[i][0]
        for j in range(1,col):
            dp[0][j]=dp[0][j-1]+grid[0][j]
        for i in range(1,row):
            for j in range(1,col):
                dp[i][j]=grid[i][j]+min(dp[i-1][j],dp[i][j-1])
        return dp[row-1][col-1]