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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.
这道题是之前那道 Unique Paths 不同的路径 的延伸，在路径中加了一些障碍物，还是用动态规划Dynamic Programming来解，不同的是当遇到为1的点，将该位置的dp数组中的值清零，其余和之前那道题并没有什么区别，代码如下：
// DP class Solution { public: int uniquePathsWithObstacles(vector<vector<int> > &obstacleGrid) { if (obstacleGrid.empty() || obstacleGrid[0].empty()) return 0; int m = obstacleGrid.size(), n = obstacleGrid[0].size(); if (obstacleGrid[0][0] == 1) return 0; vector<int> dp(n, 0); dp[0] = 1; for (int i = 0; i < m; ++i) { for (int j = 0; j < n; ++j) { if (obstacleGrid[i][j] == 1) dp[j] = 0; else if (j > 0) dp[j] += dp[j - 1]; } } return dp[n - 1]; } };
[LeetCode] Unique Paths II 不同的路径之二
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原文地址：http://www.cnblogs.com/grandyang/p/4353680.html
