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[LeetCode] 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].

class Solution {public:    vector<vector<int> > permute(vector<int> &num) {        vector<int> te;        vector<vector<int> >res,temp;//temp里存放中间值        int len = num.size();        if(len<=0)            return res;        for(int i=0;i<len;i++)        {            te.push_back(num[i]);            temp.push_back(te);            te.clear();        }//end for                while(!temp.empty())        {            te = temp.back();            temp.pop_back();            if(te.size()==len)            {               res.push_back(te);               continue;            }                for(int i=0;i<len;i++)            {                if(find(te.begin(),te.end(),num[i])==te.end())                {                    te.push_back(num[i]);                    temp.push_back(te);                    te.pop_back();                }                        }                }//end while        return res;    }};

依然是以前堆栈的思想,但用vector实现也不错。