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Permutations

Tags : array, backtracking, leetcode, cpp, medium

Problem Statement - link #

Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order.

Examples #

Example 1:

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

Example 2:

Input: nums = [0,1]
Output: [[0,1],[1,0]]

Example 3:

Input: nums = [1]
Output: [[1]]

Constraints #

Solutions #


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