Unique Paths II

Follow up for "":

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.

 

与上题差别不大，只需要判断有障碍置零即可。

对于首行首列，第一个障碍及之后的路径数均为0

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