leetcode 63 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.

Note: m and n will be at most 100.

这道题就是上一道题的延伸，相当于上一道题就是给定了一个m*n的矩阵，而且全是0，这里位置1表示的不能走的地方。所以在上一个版本上修正。

区别就是在于如果遇到1的时候的处理方式不同。

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