class Solution(object):
def minPathSum(self, grid):
"""
:type grid: List[List[int]]
:rtype: int
"""
# 注意初始化
# m x n
m = len(grid)
n = len(grid[0])
# init dp
dp = [[0]*n for _ in range(m)]
dp[0][0] = grid[0][0]
# 初始化边界的情况,避免padding
# init row
for i in range(1,n):
dp[0][i] = dp[0][i-1]+grid[0][i]
# init col
for j in range(1,m):
dp[j][0] = dp[j-1][0] + grid[j][0]
# 打表剩下的位置
for i in range(1,m):
for j in range(1,n):
dp[i][j] = min(dp[i-1][j],dp[i][j-1])+grid[i][j]
return dp[-1][-1]