leetcode 63. Unique Paths II

62题题目见上个帖子

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.

 

只需要在62题基础上加上不能走的判断即可

 

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