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]]

与Unique Paths 仅仅是加入了障碍物 动态方程没有改变 至少在 位置（i,j）有障碍物的话 要直接置值为0 其次在初始化得到时候 也有动态方程 ggrid[0][i]=grid[0][i-1];代码如下：

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