LeetCode_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]

]

 

he total number of unique paths is 2.

 

Note: m and n will be at most 100.

　　同Unique Paths的DP类似。

class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int> > &obstacleGrid) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        int m = obstacleGrid.size();
        int n = obstacleGrid[0].size();
        vector<vector<int>> grid(m, vector<int>(n,0));
        for(int i = 0; i< n; i++)
            if(obstacleGrid[0][i] ==0) grid[0][i] = 1;
            else break;
        for(int i = 0; i< m; i++)
            if(obstacleGrid[i][0] == 0) grid[i][0] = 1;
            else break;
            
        for(int i = 1; i< m; i++)
          for(int j = 1; j< n; j++)
                if(obstacleGrid[i][j] == 0)
                   grid[i][j] = grid[i-1][j] + grid[i][j-1];
        
        return grid[m-1][n-1];
    }
};