LeetCode刷题【Array】 Unique Paths II

题目：

Follow up for "Unique Paths":

Now consider if some obstacles are added to the grids. How many unique paths would there be?

An obstacle and empty space is marked as 

1

 and 

0

 respectively
in the grid.

For example,

There is one obstacle in the middle of a 3x3 grid as illustrated below.

[
[0,0,0],
[0,1,0],
[0,0,0]
]

The total number of unique paths is 

2

.

Note: m and n will be at most 100.
解决方法一：Runtime: 2
ms
public class Solution {
public int uniquePathsWithObstacles(int[][] obstacleGrid) {
if(null==obstacleGrid||obstacleGrid.length<=0) return 0;
for(int i=0; i<obstacleGrid.length;i++){
for(int j=0;j<obstacleGrid[i].length;j++){
if(obstacleGrid[i][j]==1) obstacleGrid[i][j]=0;
else if(i==0&&j==0) obstacleGrid[i][j]=1;
else if(i==0) obstacleGrid[i][j]=obstacleGrid[i][j-1];
else if(j==0) obstacleGrid[i][j]=obstacleGrid[i-1][j];
else
obstacleGrid[i][j]=obstacleGrid[i-1][j]+obstacleGrid[i][j-1];
}
}
return obstacleGrid[obstacleGrid.length-1][obstacleGrid[0].length-1];
}
}
参考：

【1】https://leetcode.com/