46. Permutations

解法一：深度优先搜索

class Solution {
public:
    vector<vector<int>> permute(vector<int>& nums) {
        vector<vector<int>> result;
        if(nums.empty()){
            return result;
        }
        vector<int> list;
        dfs(result, list, nums);
        return result;
    }
private:
    void dfs(vector<vector<int>> &result, vector<int> &list, vector<int> nums){
        if(list.size() == nums.size()){
            result.push_back(list);
            return;
        }
        for(int i = 0; i < nums.size(); i++){
            if(find(list.begin(), list.end(), nums[i]) != list.end()){
                continue;
            }
            list.push_back(nums[i]);
            dfs(result, list, nums);
            list.pop_back();
        }
        return;
    }
};