【leetcode】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.

C++

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