[Leetcode]Unique Path II

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Unique Paths II My Submissions Question
Total Accepted: 51318 Total Submissions: 180828 Difficulty: Medium
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.

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一道没啥难度的题，把不可达的位置强制置为0即可，一次AC

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

P.S 空间复杂度或许可以利用滚动数组降低下？睡觉时候想一想，想出来了更新

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