80分，TLE两个点

#include<bits/stdc++.h>
using namespace std;
list<int> a;
int main() {
    int n;
    cin>>n;
    a.push_back(1);
    for (int i=1;i<=n;i++) {
        int x;
        cin>>x;
        if (x==1) {
            int y,z;
            cin>>z>>y;
            auto it=find(a.begin(),a.end(),z);
            if (it!=a.end()) {
               a.insert(next(it),y);
            }
        }
        if (x==2) {
            int y;
            cin>>y;
            auto it=find(a.begin(),a.end(),y);
            if (it!=a.end()&&next(it)!=a.end()) {
                cout<<*next(it)<<endl;
            } else {
                cout<<"0"<<endl;
            }  
        }
        if (x==3) {
            int y;
            cin>>y;
            auto found=find(a.begin(),a.end(),y);
            if (found!=a.end()) {
                auto it=next(found); 
                if (it!=a.end()) a.erase(it);
            } 
        }
    }
}