# LeetCode – Unique Paths II (Java)

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.

**Java 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; //left column for(int i=1; i<m; i++){ if(obstacleGrid[i][0]==1){ dp[i][0] = 0; }else{ dp[i][0] = dp[i-1][0]; } } //top row for(int i=1; i<n; i++){ if(obstacleGrid[0][i]==1){ dp[0][i] = 0; }else{ dp[0][i] = dp[0][i-1]; } } //fill up cells inside 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-1][j]+dp[i][j-1]; } } } return dp[m-1][n-1]; } |

<pre><code> String foo = "bar"; </code></pre>