[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。