问题描述 主要是稀奇古怪的边界条件，例如左上角是1，最左边和最上边是1，有多个1，输入为行，或者列
class Solution:
def uniquePathsWithObstacles(self, obstacleGrid: List[List[int]]) -> int:
m = len(obstacleGrid)
n = len(obstacleGrid[0])
dp = [0]*m
if obstacleGrid[0][0]:
return 0
dp[0] = 1
for i in range(1,m):
if obstacleGrid[i][0]:
dp[i] = 0
else:
dp[i] = dp[i-1]
for i in range(1,n):
if obstacleGrid[0][i]:
dp[0] = 0
for j in range(1,m):
if obstacleGrid[j][i]:
dp[j] = 0
else:
dp[j]+=dp[j-1]
return dp[m-1]运行结果：
在第一列的初始化用上break，速度大大提升
class Solution:
def uniquePathsWithObstacles(self, obstacleGrid: List[List[int]]) -> int:
m = len(obstacleGrid)
n = len(obstacleGrid[0])
dp = [0]*m
if obstacleGrid[0][0]:
return 0
dp[0] = 1
for i in range(1,m):
if obstacleGrid[i][0]:
break
else:
dp[i] = 1
for i in range(1,n):
if obstacleGrid[0][i]:
dp[0] = 0
for j in range(1,m):
if obstacleGrid[j][i]:
dp[j] = 0
else:
dp[j]+=dp[j-1]
return dp[m-1]
