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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.
分析：动态规划+滚动数组。代码如下：
class Solution { public: int uniquePathsWithObstacles(vector<vector<int> > &obstacleGrid) { int m = obstacleGrid.size(); if(m == 0) return 0; int n = obstacleGrid[0].size(); if(n == 0) return 0; vector<int> f(n, 0); if(obstacleGrid[0][0] == 1) return 0; f[0] = 1; for(int i = 0; i < m; i++) for(int j = 0; j < n; j++) if(obstacleGrid[i][j] == 1) f[j] = 0; else f[j] += (j == 0)?0:f[j-1]; return f[n-1]; } };
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原文地址：http://www.cnblogs.com/Kai-Xing/p/4222696.html
