Submission #1035581

#	Time	Username	Problem	Language	Result	Execution time	Memory
1035581		Warinchai	Parachute rings (IOI12_rings)	C++14	Compilation error	0 ms	0 KiB

rings

#include<bits/stdc++.h>
using namespace std;
int N;
set<int>s[2000005];
int cur=0;
int p[1000005];
int in[1000005];
int fp(int a){return p[a]==a?a:p[a]=fp(p[a]);}
void un(int a,int b){p[fp(b)]=fp(a);}
vector<int>adj[1000005];
void Init(int N_) {
    N = N_;
    for(int i=0;i<N;i++)from[i]=-1,s[0].insert(i),p[i]=i;
}
void add(vector<int>v){
    cur++;
    for(auto x:v){
        if(s[cur-1].count(x))s[cur-1].erase(x),s[cur].insert(x);
    }
    //cerr<<s[cur].size()<<":\n";
    //for(auto x:s[cur])cerr<<x<<" ";
    //cerr<<"\n";
}
void add_3(int u){
    vector<int>temp;
    temp.push_back(u);
    for(auto x:adj[u]){
        temp.push_back(x);
    }
    add(temp);
}
int vis[1000005];
int tvis[1000005];
int cycle=0;
int from[1000005];
void dfs(int u,int p=-1){
    if(tvis[u])return;
    //cerr<<"dfs:"<<u<<" "<<p<<"\n";
    from[u]=p;
    tvis[u]=1;
    for(auto x:adj[u])if(x!=p)dfs(x,u);
}
void Link(int A, int B) {
    if(s[cur].size()==0)return;
    in[A]++;
    in[B]++;
    adj[A].push_back(B);
    adj[B].push_back(A);
    if(vis[A])dfs(A,from[A]);
    if(vis[B])dfs(B,from[B]);
    if(fp(A)==fp(B)){
        if(cycle){
            if(vis[A]&&vis[B])add({A,B});
            else if(!vis[A]&&!vis[B])return void(cur++);
            else {
                if(vis[A])swap(A,B);
                int temp=A;
                while(!vis[temp]){
                    vis[temp]=1;
                    temp=from[temp];
                }
                add({A,B});
            }
        }else{
            cycle=1;
            dfs(A,B);
            int temp=B;
            vector<int>loop;
            while(temp!=A)/*cerr<<"re loop:"<<temp<<"\n",*/loop.push_back(temp),vis[temp]++,temp=from[temp];
            loop.push_back(A);
            vis[A]++;
            //cerr<<"in loop:\n";
            //for(auto x:loop)cerr<<x<<" ";
            //cerr<<"\n";
            add(loop);
        }
    }
    un(A,B);
    if(in[A]==3)add_3(A);
    if(in[B]==3)add_3(B);
    if(in[A]>3)add({A});
    if(in[B]>3)add({B});
}

int CountCritical() {
    return s[cur].size();
}

Compilation message (stderr)

rings.cpp: In function 'void Init(int)':
rings.cpp:13:25: error: 'from' was not declared in this scope
   13 |     for(int i=0;i<N;i++)from[i]=-1,s[0].insert(i),p[i]=i;
      |                         ^~~~