62. 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]
]

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 n = obstacleGrid.length;
        int m = obstacleGrid[0].length;
        int[] dp = new int[m + 1];
    
        if (obstacleGrid[0][0] != 1)
            dp[1] = 1;
    
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                dp[j + 1] = obstacleGrid[i][j] == 1 ? 0 : dp[j + 1] + dp[j];
            }
        }
    
        return dp[m];

    }
}