```
class Solution(object):
def minPathSum(self, grid):
"""
:type grid: List[List[int]]
:rtype: int
"""
m = len(grid)
n = len(grid[0])
if m < 2 or n < 2: return sum([sum(i) for i in grid])
for i in xrange(1,m):
grid[i][0] += grid[i-1][0]
for i in xrange(1,n):
grid[0][i] += grid[0][i-1]
for i in xrange(1,m):
for j in xrange(1,n):
grid[i][j] += grid[i-1][j] if grid[i-1][j] < grid[i][j-1] else grid[i][j-1]
return grid[-1][-1]
```