Submission #36807

#	Time	Username	Problem	Language	Result	Execution time	Memory
36807		mohammad_kilani	Parachute rings (IOI12_rings)	C++14	100 / 100	2332 ms	113148 KiB

rings

#include <bits/stdc++.h>
using namespace std;
const int N = 1000010;
int n , comp[N], mx , adj[N] , ans = 0 , cycles = 0 , vis[N] , vi = 0 , comp2[4][N] , con1[4][N] , con2[4][N];
vector< int > g[N];
vector< pair<int,bool> > v;
vector< pair<int,int> > v2;

int Find(int u){
	return (u == comp[u] ? u : comp[u] = Find(comp[u]));
}

int Find2(int u,int i){
	if(u == comp2[i][u]) 
		return u;
	return comp2[i][u] = Find2(comp2[i][u],i);
}

void Init(int N_) {
  n = N_;
  ans = n ;
  for(int i=0;i<n;i++) 
  	comp[i] = i;
  mx = 0 ;
  cycles = 0 ;
}


void DFS(int node,int prnt,int last){
	ans++;
	if(node == last) return;
	for(int i=0;i<(int)g[node].size();i++){
		if(g[node][i] != prnt) DFS(g[node][i],node,last);
	}
}

void DFS2(int node,int cant){
	vis[node] = vi;
	int num = 0 ;
	for(int i=0;i<(int)g[node].size();i++){
		int newnode = g[node][i];
		num += (newnode != cant);
		if(vis[newnode] == vi || newnode == cant) continue;
		DFS2(newnode,cant);
	}
	v2.push_back(make_pair(node,num));
}

void make(int u){
	v.push_back(make_pair(u,true));
	for(int i=0;i<(int)g[u].size();i++){
		v.push_back(make_pair(g[u][i],true));
	}
	ans = 0 ;
	for(int i=0;i<(int)v.size();i++){
		vi++;
		int cnt = 0 ;
		for(int j=0;j<n;j++){
			if(j == v[i].first || vis[j] == vi) continue;
			v2.clear();
			cnt = j;
			DFS2(j,v[i].first);
			if(v2.size() == 1){
				con1[i][cnt] = con2[i][cnt] = v2[0].first;
				comp2[i][v2[0].first] = cnt;
			}
			else if(v2.size() == 2){
				con1[i][cnt] = v2[0].first;
				con2[i][cnt] = v2[1].first;
				comp2[i][v2[0].first] = comp2[i][v2[1].first] = cnt;
			}
			else{
				con1[i][cnt] = con2[i][cnt] = -1;
				for(int k=0;k<(int)v2.size();k++){
					if(v2[k].second == 1) if(con1[i][cnt] == -1) con1[i][cnt] = v2[k].first; else con2[i][cnt] = v2[k].first;
					comp2[i][v2[k].first] = cnt;
				}
				if(con1[i][cnt] == -1){
					v[i].second = false;
					break;
				}
			}
		}
		ans += v[i].second;
	}
}

void Link(int a, int b) {
	if(ans == 0) return;
	if(mx < 3){
		int u = Find(a);
		int v = Find(b);
		adj[a]++;
		adj[b]++;
		g[a].push_back(b);
		g[b].push_back(a);
		if(adj[a] == 3){
			mx = 3;
			make(a);
			return ;
		}
		if(adj[b] == 3){
			mx = 3;
			make(b);
			return;
		}
		if(u == v){
			if(cycles > 0){
				ans = 0;
				return ;
			}
			cycles++;
			ans = 0 ;
			DFS(a,b,b);
		}
		else{
			comp[u] = v;
		}
		return ;
	}
	for(int i=0;i<(int)v.size();i++){
		if(v[i].second == false) continue;
		if(a == v[i].first || b == v[i].first){
			adj[v[i].first]++;
			if(adj[v[i].first] > 3 && v.size() > 1){
				int cur = v[i].first;
				ans = 1;
				v.clear();
				v.push_back(make_pair(cur,1));
				break;
			}
			continue;
		}
		int u = Find2(comp2[i][a],i);
		int vv = Find2(comp2[i][b],i);
		if(u == vv){
			v[i].second = false;
			ans--;
			continue;
		}
		if(a != con1[i][u] && a != con2[i][u]){
			v[i].second = false;
			ans--;
			continue;
		}
		if(b != con1[i][vv] && b != con2[i][vv]){
			v[i].second = false;
			ans--;
			continue;
		}
		comp2[i][u] = vv;
		if(a == con1[i][u] && b == con1[i][vv]){
			con1[i][vv] = con2[i][u];
		}
		else if(a == con2[i][u] && b == con1[i][vv]){
			con1[i][vv] = con1[i][u];
		}
		else if(a == con1[i][u] && b == con2[i][vv]){
			con2[i][vv] = con2[i][u];
		}
		else if(a == con2[i][u] && b == con2[i][vv]){
			con2[i][vv] = con1[i][u];
		}
	}
}

int CountCritical() {
  return ans;
}

Compilation message (stderr)

rings.cpp: In function 'void make(int)':
rings.cpp:75:8: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
      if(v2[k].second == 1) if(con1[i][cnt] == -1) con1[i][cnt] = v2[k].first; else con2[i][cnt] = v2[k].first;
        ^

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