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]
]

public class Solution {
    public int uniquePathsWithObstacles(int[][] obstacleGrid) {
        int m = obstacleGrid.length,n = obstacleGrid[0].length;
        int[][] map = new int[m][n];
        for(int i = 0 ; i < m; i++){
            for(int j = 0; j < n; j++){
                if(obstacleGrid[i][j] == 1) continue;
                else if(i == 0 && j == 0) map[i][j] = 1;
                else if(i == 0) map[i][j] = map[i][j-1];
                else if(j == 0) map[i][j] = map[i-1][j];
                else map[i][j] =map[i-1][j]+map[i][j-1];
            }
        }

        return map[m-1][n-1];
    }
}