Permutations
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].
解法一：递归
class Solution { public: vector<vector<int> > permute(vector<int> &num) { vector<vector<int> > result; vector<int> cur = num; Helper(result, cur, 0); return result; } void Helper(vector<vector<int> >& result, vector<int> cur, int start) { if(start == cur.size()-1) result.push_back(cur); else { for(int i = start; i < cur.size(); i ++) { swap(cur[start], cur[i]); Helper(result, cur, start+1); swap(cur[i], cur[start]); } } } };
原文：http://www.cnblogs.com/ganganloveu/p/4161395.html