LeetCode--No.63--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.

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

是之前那篇的变种，加了一个判断就好。