题解 | #牛群的标签和#

#include <vector>
class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param nums int整型vector 
     * @param target int整型 
     * @return int整型vector<vector<>>
     */
    vector<vector<int>> result;
    vector<int> path;
    void backTracking(vector<int>& nums,int target,int startIndex,int sumNum)
    {
        if (path.size() == 4 && sumNum == target)
        {
            vector<int> temp;
            temp.assign(path.begin(), path.end());
            sort(temp.begin(),temp.end());
            result.push_back(temp);
            return;
        }
        for (int i = startIndex;i < nums.size();++i)
        {
            path.push_back(nums[i]);
            sumNum += nums[i];
            backTracking(nums, target, i + 1, sumNum);
            sumNum -= nums[i];
            path.pop_back();
        }
    }
    vector<vector<int>> fourSum(vector<int>& nums, int target) 
    {
        // write code here
        set<vector<int>> ans;
        backTracking(nums, target, 0, 0);
        for (auto it : result)
        {
            ans.insert(it);
        }
        result.clear();
        for (auto it : ans)
        {
            result.push_back(it);
        }
        return result;
    }
};

可是我只会回溯啊