49_Permutation _leetcode.cpp

/*49 . problem  leetcode
    permutations of integer*/

#include<bits/stdc++.h>
using namespace std;
class Solution {
private:
    void  solve(vector<int> nums,vector<vector<int>>& ans, int index){
        //base case
        if(index>=nums.size()){
            ans.push_back(nums);
            return ;

        }
        for (int j=index;j<nums.size();j++){
            swap(nums[index],nums[j]);
            solve(nums,ans,index+1);
            //backtrack
            swap(nums[index],nums[j]);

            
        }
    }


public:
    vector<vector<int>> permute(vector<int>& nums) {
        vector<vector<int>> ans;
        int index=0;
        solve(nums,ans,index);
        return ans;
    }
};