Submission #49004

#	Time	Username	Problem	Language	Result	Execution time	Memory
49004		Namnamseo	Parachute rings (IOI12_rings)	C++17	100 / 100	832 ms	50460 KiB

rings

#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> pp;

vector<pp> links;

int n;

struct simulator {
	int deg [1000010];
	int oppo[1000010];
	bool crit;
	int R;

	void init(int rem){
		R=rem;
		for(int i=0; i<n; ++i) deg[i]=0, oppo[i]=i;
		crit=true;
		for(auto& q:links){
			update(q.first, q.second);
		}
	}

	void update(int a,int b){
		if(!crit) return;
		if(a!=R && b!=R){
			++deg[a], ++deg[b];
			int p=oppo[a], q=oppo[b];
			if(b==p){
				crit=false;
				return;
			}
			oppo[p]=q; oppo[q]=p;
			if(deg[a]>=3 || deg[b]>=3){
				crit=false;
			}
		}
	}
};

int par[1000010];
int sz [1000010];
int cyc_cnt;
int cyc_size;

int R(int x){
	return (par[x]==x)?x:(par[x]=R(par[x]));
}

void join(int a,int b){
	a=R(a); b=R(b);
	if(a == b){
		++cyc_cnt;
		cyc_size += sz[a];
	} else {
		sz[b] += sz[a];
		par[a] = b;
	}
}

void Init(int n_) {
	n=n_;
	for(int i=0; i<n; ++i) par[i]=i, sz[i]=1;
}

int first_deg[1000010];
bool isSim;

simulator ss[4];

void Link(int A, int B) {
if(!isSim){
	++first_deg[A]; ++first_deg[B];
	links.push_back({A, B});
	join(A,B);

	int thr = -1;
	if(first_deg[A] == 3) thr = A;
	if(first_deg[B] == 3) thr = B;

	if(thr != -1){
		vector<int> inj;
		for(pp& l:links){
			int a,b; tie(a,b)=l;
			if(a==thr) inj.push_back(b);
			if(b==thr) inj.push_back(a);
		}
		ss[3].init(thr);
		for(int i=0; i<3; ++i) ss[i].init(inj[i]);
		isSim = true;
	}
} else {

	for(int i=0; i<4; ++i)
		ss[i].update(A, B);
}
}

int CountCritical() {
	if(!isSim){
		if(cyc_cnt >= 2)
			return 0;
		else return cyc_cnt ? cyc_size : n;
	}
	int ans=0;
	for(int i=0; i<4; ++i) if(ss[i].crit) ++ans;
	return ans;
}

• Subtask 1: 20 / 20
• Subtask 2: 17 / 17
• Subtask 3: 18 / 18
• Subtask 4: 14 / 14
• Subtask 5: 31 / 31