Leetcode 46 Permutations

Given a collection of distinct numbers, return all possible permutations.

For example,
[1,2,3] have the following permutations:

[  [1,2,3],  [1,3,2],  [2,1,3],  [2,3,1],  [3,1,2],  [3,2,1]]

找出全排列。

直接用next_permutation实现

class Solution {public:    vector<vector<int>> permute(vector<int>& nums) {        vector<vector<int>> result;        sort(nums.begin(),nums.end());        do        {            result.push_back(nums);        }while(next_permutation(nums.begin(),nums.end()));        return result;    }};

DFS实现

class Solution {public:    void dfs(vector<vector<int>> &result,vector<int> nums,vector<int> now)    {        if(nums.size() == 0)        {            result.push_back(now);            return ;        }        for(int i=0;i<nums.size();i++)        {            now.push_back(nums[i]);            vector<int> temp=nums;            temp.erase(temp.begin()+i);            dfs(result,temp,now);            now.pop_back();        }    }    vector<vector<int>> permute(vector<int>& nums)     {        vector<vector<int>> result;        vector<int> now;        dfs(result,nums,now);        return result;    }};