Submission #578238

#	Time	Username	Problem	Language	Result	Execution time	Memory
578238		WongChun1234	Parachute rings (IOI12_rings)	C++14	37 / 100	2878 ms	190828 KiB

rings

#include<bits/stdc++.h>
using namespace std;
const int N=1000050;
int n,ord[N],par[N],cyc,cycgrp[N],cn[N];
vector<int> must,adj[N],preord;
vector<pair<int,int>> lz;
bool failed,incyc[N],vis[N];
map<pair<int,int>,bool> hv;

void Init(int N_) {
	n=N_;
	failed=0;
	cyc=-1;
	preord=must={};
	for (int i=0;i<n;i++) ord[i]=0,adj[i].clear(),par[i]=cycgrp[i]=i,incyc[i]=vis[i]=0,cn[i]=-1;
}

void checknode(int u){
	if (must.empty()){
		must.push_back(u);
		for (int i=0;i<3;i++) must.push_back(adj[u][i]);
	}else{
		vector<int> nw={};
		for (int i:must){
			bool ok=0;
			if (i==u) ok=1;
			for (int j=0;j<3;j++) if (i==adj[u][j]) ok=1;
			if (ok) nw.push_back(i);
		}
		must=nw;
		if (must.empty()) failed=1;
	}
}

void failnode(int u){
	vector<int> nw={};
	for (int i:must){
		bool ok=0;
		if (i==u) ok=1;
		if (ok) nw.push_back(i);
	}
	must=nw;
	if (must.empty()) failed=1;
}

int find(int u){
	return (par[u]==u?u:par[u]=find(par[u]));
}

int ff(int u){
	return (cycgrp[u]==u?u:cycgrp[u]=ff(cycgrp[u]));
}

void merge(int u,int v){
	if (cn[ff(u)]!=-1&&cn[ff(v)]!=-1&&cn[ff(u)]!=cn[ff(v)]){
		cycgrp[ff(u)]=ff(v);
		cn[ff(v)]=INT_MAX;
	}else if (cn[ff(u)]!=-1){
		cycgrp[ff(v)]=ff(u);
	}else{
		cycgrp[ff(u)]=ff(v);
	}
}

void dfs(int u,int v){
	vis[u]=1;
	preord.push_back(u);
	for (int i:adj[u]){
		if (i==v){
			incyc[v]=1;
			for (int j:preord) incyc[j]=1;
			if (must.empty()){
				must.push_back(v);
				for (int j:preord) must.push_back(j);
			}
			return;
		}else if (vis[i]) continue;
		dfs(i,v);
	}
	preord.pop_back();
}

int cnt,pp[N],ecnt[N];
int fff(int u){
	return (pp[u]==u?u:pp[u]=fff(pp[u]));
}
int cccnt=0;
int CountCritical() {
	//for (int i:must) cerr<<i<<" ";
	//cerr<<"!\n";
	int ret;
	if (failed) ret=0;
	else if (must.size()) ret=must.size();
	else ret=n;
	return ret;
	/*cnt=0;
	for (int i=0;i<n;i++){
		bool ok=1;
		for (int j=0;j<n;j++) pp[j]=j,ecnt[j]=0;
		for (auto j:lz){
			if (j.first==i||j.second==i) continue;
			if (fff(j.first)==fff(j.second)) ok=0;
			ecnt[j.first]++; ecnt[j.second]++;
			if (ecnt[j.first]>2||ecnt[j.second]>2) ok=0;
			pp[fff(j.first)]=j.second;
			if (!ok) break;
		}
		cnt+=ok;
	}
	if (ret>cnt) assert(cnt==0);
	//tle cnt!=0
	//re cnt=0
	return ret;*/
}

void Link(int u, int v) {
	hv[{u,v}]=1;
	ord[u]++; ord[v]++;
	adj[u].push_back(v); adj[v].push_back(u);
	if (failed) goto skip;
	lz.push_back({u,v});
	if (ord[u]==3){
		checknode(u);
	}else if (ord[u]>=4){
		failnode(u);
	}
	if (failed) goto skip;
	if (ord[v]==3){
		checknode(v);
	}else if (ord[v]>=4){
		failnode(v);
	}
	if (failed) goto skip;
	if (find(u)==find(v)){
		if (cyc==-1){
			adj[u].pop_back(); adj[v].pop_back();
			dfs(u,v);
			adj[u].push_back(v); adj[v].push_back(u);
			vector<int> nw={};
			for (int i:must){
				if (incyc[i]) nw.push_back(i);
			}
			must=nw;
			if (must.empty()) failed=1;
			cyc=find(u);
			for (auto i:lz){
				if (incyc[i.first]^incyc[i.second]){
					if (incyc[i.first]){
						cn[ff(i.second)]=i.first;
					}else{
						cn[ff(i.first)]=i.second;
					}
				}
				if (incyc[i.first]||incyc[i.second]) continue;
				if (ff(i.first)!=ff(i.second)){
					merge(i.first,i.second);
				}
			}
		}else if (find(cyc)==find(u)){
			//cerr<<ff(u)<<"--"<<ff(v)<<"\n";
			if (incyc[u]||incyc[v]){
				if (incyc[u]&&incyc[v]){
					failed=1;
				}else if (incyc[u]){
					if (cn[ff(v)]=INT_MAX) failed=1;
					if (cn[ff(v)]!=-1) cn[ff(v)]=INT_MAX;
					else cn[ff(v)]=u;
				}else{
					if (cn[ff(u)]=INT_MAX) failed=1;
					if (cn[ff(u)]!=-1) cn[ff(u)]=INT_MAX;
					else cn[ff(u)]=v;
				}
			}else{
				//cerr<<cn[ff(u)]<<"uwuuwuw"<<cn[ff(v)]<<"\n";
				if (cn[ff(u)]==INT_MAX||cn[ff(v)]==INT_MAX) failed=1;
				if (!(hv[{cn[ff(u)],cn[ff(v)]}]||hv[{cn[ff(v)],cn[ff(u)]}])) failed=1;
				if (ff(u)==ff(v)) failed=1;
				merge(u,v);
			}
		}else{
			failed=1;
		}
	}else{
		par[find(u)]=v;
		if (cyc!=-1){
			if (!(incyc[u]||incyc[v])) merge(u,v);
			else{
				if (incyc[u]) swap(u,v);
				if (incyc[v]){
					cn[ff(u)]=v;
				}
			}
		}
	}
	skip:;
	//cerr<<CountCritical()<<"\n";
}

/*
9 11
0 1
1 2
2 3
3 4
4 5
3 6
5 0
6 7
6 4
5 8
8 7
*/

Compilation message (stderr)

rings.cpp: In function 'void Link(int, int)':
rings.cpp:165:19: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
  165 |      if (cn[ff(v)]=INT_MAX) failed=1;
      |                   ^
rings.cpp:169:19: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
  169 |      if (cn[ff(u)]=INT_MAX) failed=1;
      |                   ^

• Subtask 1: 20 / 20
• Subtask 2: 17 / 17
• Subtask 3: 0 / 18
• Subtask 4: 0 / 14
• Subtask 5: 0 / 31