Given a collection of numbers, return all possible permutations.For example,
[1,2,3]?have the following permutations:
[1,2,3],?[1,3,2],?[2,1,3],?[2,3,1],?[3,1,2], and?[3,2,1].? Solve this problem
[解題思路]
遞歸，用標志位記錄已使用數字。

[Code]
1: vector<vector<int> > permute(vector<int> &num) {
2: // Start typing your C/C++ solution below
3: // DO NOT write int main() function
4: vector<vector<int> > coll;
5: vector<int> solution;
6: if(num.size() ==0) return coll;
7: vector<int> visited(num.size(), 0);
8: GeneratePermute(num, 0, visited, solution, coll);
9: return coll;
10: }
11: void GeneratePermute(vector<int> & num, int step, vector<int>& visited, vector<int>& solution, vector<vector<int> >& coll)
12: {
13: if(step == num.size())
14: {
15: coll.push_back(solution);
16: return;
17: }
18: for(int i =0; i< num.size(); i++)
19: {
20: if(visited[i] == 0)
21: {
22: visited[i] = 1;
23: solution.push_back(num[i]);
24: GeneratePermute(num, step+1, visited, solution, coll);
25: solution.pop_back();
26: visited[i] =0;
27: }
28: }
29: }

轉載于:https://www.cnblogs.com/codingtmd/archive/2012/12/30/5078978.html

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