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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]); } } } };
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原文地址:http://www.cnblogs.com/ganganloveu/p/4161395.html