Leetcode46. Permutations全排列

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] ]

class Solution {
public:
    vector<vector<int> >res;
    vector<int> visit;
    int size;
    vector<vector<int> > permute(vector<int>& nums)
    {
        int len = nums.size();
        if(len == 0)
            return res;
        size = len;
        visit = vector<int>(len, 0);
        vector<int> temp;
        DFS(nums, temp, 0);
        return res;
    }

    void DFS(vector<int>& nums, vector<int> &temp, int len)
    {
        if(len == size)
        {
            res.push_back(temp);
        }
        for(int i = 0; i < size; i++)
        {
            if(visit[i] == 1)
                continue;
            visit[i] = 1;
            temp.push_back(nums[i]);
            DFS(nums, temp, len + 1);
            visit[i] = 0;
            temp.pop_back();
        }
    }
};