题解 | 动态整数集最近值提取

#include<bits/stdc++.h>
using namespace std;set<int>s;int p,x,a,b;
int main(){for(cin>>x;cin>>p>>x;){
        if(p<2){if(s.count(x))puts("Already Exist");s.insert(x);}
        else if(s.size()){
                if(x<=(p=*s.begin()))cout<<p<<endl,s.erase(p);
                else if(x>=(p=*--s.end()))cout<<p<<endl,s.erase(p);
                else{auto it=s.lower_bound(x);a=*it,b=*--it;
                    if(x-b>a-x)b=a;cout<<b<<endl,s.erase(b);
                }
            }
        else puts("Empty");
    }
}

给出一份不那么长的解