LeetCode-46. 全排列

給定一個沒有重複數字的序列，返回其所有可能的全排列。

示例:

輸入: [1,2,3]
輸出:
[
  [1,2,3],
  [1,3,2],
  [2,1,3],
  [2,3,1],
  [3,1,2],
  [3,2,1]
]

 

#include <iostream>
#include <vector>
#include <stdio.h>
using namespace std;

class Solution {
public:
    vector<vector<int>> permute(vector<int>& nums) {
        int n = nums.size();
        vector<vector<int>> res;
        backTrace(n,0,nums,res);
        return res;
    }

    void backTrace(int n,
                   int first,
                   vector<int>& nums,
                   vector<vector<int>>& res){
        if(first==n){
            res.push_back(nums);
        }
        for(int i=first;i<n;i++){
            swap(nums[i],nums[first]);
            backTrace(n,first+1,nums,res);
            swap(nums[i],nums[first]);
        }
    }
};


int main(){
    vector<int> test ={1,2,3};
    vector<vector<int>> res;
    Solution *ps = new Solution();
    res = ps->permute(test);

    for(int i=0;i<res.size();i++){
        vector<int>temp = res[i];
        for(int j=0;j<temp.size();j++){
            cout<<temp[j];
        }
        cout<<endl;
    }
    return 0;
}