clasLeetcode刷题笔记(c++)

class Solution {
public:
    vector> threeSum(vector& nums) {
        vector>out;
        if(nums.empty())return out;
        int n=nums.size();
        unordered_sethashset;
        if(n<3)return out;
        for(int i=0;i
            unordered_sethashmap;
            for(int j=i+1;j
                vectorb;
                auto it=hashmap.find(-nums[i]-nums[j]);
                if(it!=hashmap.end()){
                    b.emplace_back(nums[i]);
                    b.emplace_back(*it);
                    b.emplace_back(nums[j]);
                    sort(b.begin(),b.end());
                    string s;
                    for(int k:b)s+=to_string(k);
                    if(!hashset.count(s)){
                        out.emplace_back(b);
                        hashset.insert(s); 
                    }                   
                }                    
                else hashmap.insert(nums[j]);
            }
        }

        return out;
    }
};

超时，待更新。。。