Given a collection of distinct integers, return all possible permutations.

Example:

Input: [1,2,3]Output:[  [1,2,3],  [1,3,2],  [2,1,3],  [2,3,1],  [3,1,2],  [3,2,1]]

 

AC code:

class Solution {public:    vector
     
      
       > permute(vector
       
        & nums) {        vector
        
         
          > v;        iteration(nums, v, 0);        return v;    }        void iteration(vector
          
           & nums, vector
           
            
             >& v, int begin) { if (begin >= nums.size()) { v.push_back(nums); return; } for (int i = begin; i < nums.size(); ++i) { swap(nums[begin], nums[i]); iteration(nums, v, begin+1); swap(nums[begin], nums[i]); } }};
            
           
          
         
        
       
      
     

Runtime: 12 ms, faster than 42.11% of C++ online submissions for Permutations.