Unique Paths II

-----QUESTION-----

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.

-----SOLUTION-----

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