Leetcode 46 Full arrangement (February 15, 2022)

  Give an array without duplicate numbers nums , Back to its All possible permutations . You can In any order Return to the answer .

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]]

Tips ：

1 <= nums.length <= 6
-10 <= nums[i] <= 10
nums All integers in Different from each other

source ： Power button （LeetCode）
link ：https://leetcode-cn.com/problems/permutations

Method 1 ：DFS+ to flash back

C++ Submission ：

class Solution {
    
public:
    void backtrack(vector<vector<int>>& res, vector<int>& output, int first, int len){
    
        if(first == len){
    
            res.emplace_back(output);
            return;
        }

        for(int i = first; i < len; ++i){
    
            swap(output[first], output[i]);
            backtrack(res, output, first + 1, len);
            swap(output[first], output[i]);
        }
    }

    vector<vector<int>> permute(vector<int>& nums) {
    
        vector<vector<int>> res;
        backtrack(res, nums, 0, int(nums.size()));
        return res;
    }
};