64.py

class Solution(object):
    def minPathSum(self, grid):
        """
        :type grid: List[List[int]]
        :rtype: int
        """
        #Edge
        if not grid:
            return

        #Grid = [row][col]
        r = len(grid)
        c = len(grid[0])

        #Create dp matrix
        dp = [[0 for _ in xrange(c)] for _ in xrange(r)]

        dp[0][0] = grid[0][0]

        for i in xrange(1, r):
            dp[i][0] = dp[i-1][0] + grid[i][0]

        for i in xrange(1, c):
            dp[0][i] = dp[0][i-1] + grid[0][i]

        # The rest:
        for i in xrange(1, r):
            for j in xrange(1, c):
                dp[i][j] = min(dp[i-1][j], dp[i][j-1]) + grid[i][j]

        return dp[-1][-1]