Unique Paths II

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.

加入对矩阵元素是否为1的判断来初始化数组，只能使用二维数组。

public class Solution {    public int uniquePathsWithObstacles(int[][] obstacleGrid) {       if(obstacleGrid==null||obstacleGrid.length<=0)return 0;int m=obstacleGrid.length;int n=obstacleGrid[0].length;if(obstacleGrid[0][0]==1||obstacleGrid[m-1][n-1]==1)return 0;int[][] dp=new int[m][n];dp[0][0]=1;for(int i=1;i<m;i++){if(obstacleGrid[i][0]==1)dp[i][0]=0;elsedp[i][0]=dp[i-1][0];}for(int i=1;i<n;i++){if(obstacleGrid[0][i]==1)dp[0][i]=0;elsedp[0][i]=dp[0][i-1];}for(int i=1; i<m; ++i){              for(int j=1; j<n; ++j){             if(obstacleGrid[i][j]==1)    dp[i][j]=0;            else            dp[i][j]+=dp[i][j-1]+dp[i-1][j];              }          }return dp[m-1][n-1];     }}