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