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]
]

Solution:

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