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class Solution {//DFSpublic:	vector
   
    
      > permute(vector
     
       &num) {		// Start typing your C/C++ solution below		// DO NOT write int main() function		int n = num.size();		if(0 == n) return vector
      
       
         >();		sort(num.begin(), num.end());		vector
        
          used(num.size(), false); vector
         
          
           > ans; vector
           
             path; permute_aux(n, used, path, ans, num); return ans; } void permute_aux( int n, vector
            
             & used, vector
             
              & path, vector
              
               
                >& ans, const vector
                
                 & num ) { //throw std::exception("The method or operation is not implemented."); if(0 == n) { ans.push_back(path); return; } for (int i = 0; i < used.size(); ++i) { if(false == used[i]) { used[i] = true; path.push_back(num[i]); permute_aux(n-1, used, path, ans, num); used[i] = false; path.pop_back(); } } }};
                
               
              
             
            
           
          
         
        
       
      
     
    
   

second time

class Solution {public:    void permuteUtil(vector
   
    & num, vector
    
     & used, vector
     
      & path, vector
      
       
         >& allPath)    {        if(path.size() == num.size())        {            allPath.push_back(path);            return ;        }        for(int i = 0; i < num.size(); ++i)        {            if(!used[i])            {                used[i] = true;                path.push_back(num[i]);                permuteUtil(num, used, path, allPath);                path.pop_back();                used[i] = false;            }        }    }    vector
        
         
           > permute(vector
          
            &num) { // Start typing your C/C++ solution below // DO NOT write int main() function vector
           
            
              > allPath; vector
             
               path; vector
              
                used(num.size(), false); permuteUtil(num, used, path, allPath); return allPath; }};
              
             
            
           
          
         
        
       
      
     
    
   

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