Leetcode (Python): Minimum Path Sum

Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path.

Note: You can only move either down or right at any point in time.

Solution:

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