leetcode63 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.

class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
        int ans=0;
        int m=obstacleGrid.size();
        if(!m)
            return ans;
        int n=obstacleGrid[0].size();
        
        vector<int> jlist(n,0);
        for(int i=n-1;i>=0;i--)
        {
            if(obstacleGrid[m-1][i]==1)
                break;
            else
                jlist[i]=1;
        }
        
        for(int i=m-2;i>=0;i--)
        {
            for(int j=n-1;j>=0;j--)
            {
                if(j==n-1)
                {
                    if(obstacleGrid[i][j]==1)
                        jlist[j]=0;
                }
                else
                {
                
                if(obstacleGrid[i][j]==1)
                    jlist[j]=0;
                else
                    jlist[j]+=jlist[j+1];
                    
                }
                
                
            }
        }
        return jlist[0];
    }
};