46.全排列.cpp

/*
 * @lc app=leetcode.cn id=46 lang=cpp
 *
 * [46] 全排列
 *
 * https://leetcode-cn.com/problems/permutations/description/
 *
 * algorithms
 * Medium (72.13%)
 * Likes:    414
 * Dislikes: 0
 * Total Accepted:    51.5K
 * Total Submissions: 71.3K
 * Testcase Example:  '[1,2,3]'
 *
 * 给定一个没有重复数字的序列，返回其所有可能的全排列。
 * 
 * 示例:
 * 
 * 输入: [1,2,3]
 * 输出:
 * [
 * ⁠ [1,2,3],
 * ⁠ [1,3,2],
 * ⁠ [2,1,3],
 * ⁠ [2,3,1],
 * ⁠ [3,1,2],
 * ⁠ [3,2,1]
 * ]
 * 
 */

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

// @lc code=end