gistfile1.cpp

https://oj.leetcode.com/problems/permutations/
class Solution {
public:
    vector<vector<int>> permute(vector<int> &num) {
        vector<vector<int>> res;
        
        if(num.size() == 0) {
            return res;
        }
        
        permute(0, num.size(), num, res);
        
        return res;
    }
    
    void permute(int i, int n, vector<int>& num, vector<vector<int>>& res) {
        if(i >= n-1) {
            res.push_back(num);
            
            return;
        }
        
        for(int k=i; k<num.size() ; ++k) {
            swap(num[i],num[k]);
            permute(i+1,n,num,res);
            swap(num[i], num[k]);
        }
    }
};