```
class Solution(object):
def minPathSum(self, grid):
"""
:type grid: List[List[int]]
:rtype: int
"""
m = len(grid)
if m == 0: return 0
n = len(grid[0])
if n == 0: return 0
# initialize DP table
table = [[0 for j in range(n)] for i in range(m)]
table[0][0] = grid[0][0]
for j in range(1, n): table[0][j] = table[0][j-1] + grid[0][j]
for i in range(1, m): table[i][0] = table[i-1][0] + grid[i][0]
# DP
for i in range(1, m):
for j in range(1, n):
table[i][j] = min(table[i-1][j], table[i][j-1]) + grid[i][j]
return table[m-1][n-1]
```