Submission #1079091

#	Time	Username	Problem	Language	Result	Execution time	Memory
1079091		Gray	Simurgh (IOI17_simurgh)	C++17	0 / 100	64 ms	3900 KiB

simurgh

#include "simurgh.h"
#include <bits/stdc++.h>
using namespace std;
#define ll int
#define ff first
#define ss second
#define ln "\n"
#define ld long double


vector<pair<ll, ll>> e;
vector<vector<ll>> A;

// Slow version
vector<ll> checka;
void dfs(ll u, vector<bool> &vis, ll mask){
	vis[u]=1;
	for (auto i:A[u]){
		if (mask&(1<<i)){
			ll v = e[i].ff^e[i].ss^u;
			if (vis[v]) continue;
			dfs(v, vis, mask);
		}
	}
}
bool check(ll mask, ll n, ll m){
	checka.clear();
	vector<bool> vis(n);
	dfs(0, vis, mask);
	for (ll i=0; i<n; i++) if (!vis[i]) return 0;
	for (ll i=0; i<m; i++){
		if (mask&(1<<i)) checka.push_back(i);
	}
	return 1;
}
vector<int> find_roads_slow(int _n, vector<int> u, vector<int> v) {
	int n=_n, m=u.size();
	e.resize(m); A.clear(); A.resize(n);
	for (ll i=0; i<m; i++){
		e[i]={u[i], v[i]};
		A[u[i]].push_back(i); A[v[i]].push_back(i);
	}
	vector<ll> ans;
	for (ll i=0; i<(1ll<<m); i++){
		if (__builtin_popcount(i)==n-1){
			if (check(i, n, m)) {
				ll ret = count_common_roads(checka);
				if (ret==n-1){
					ans=checka; break;
				}
			}
		}
	}
	return ans;
}


ll n, m;
vector<bool> isBridge;

void findBridge(ll u, ll p, vector<ll> &tin, vector<ll> &tmin, ll &timer){
	tin[u]=tmin[u]=timer++;
	for (auto i:A[u]){
		ll v = e[i].ff^e[i].ss^u;
		if (v==p) continue;
		if (tin[v]==-1) findBridge(v, u, tin, tmin, timer);
		tmin[u]=min(tmin[u], tmin[v]);
		if (tin[u]<tmin[v]){
			isBridge[i]=1;
		}
	}
}

vector<bool> noroyal;

void findST(ll u, vector<bool> &vis, vector<ll> &edges){
	vis[u]=1;
	for (auto i:A[u]){
		if (noroyal[i]) continue;
		ll v = e[i].ff^e[i].ss^u;
		if (vis[v]) continue;
		edges.push_back(i);
		findST(v, vis, edges);
	}
}

struct DSU{
	vector<ll> p;
	ll sz;
	DSU(ll N){
		sz=N;
		p.resize(N+1, -1);
	}
	ll get(ll x){
		return (p[x]==-1?x:p[x]=get(p[x]));
	}
	bool unite(ll u, ll v){
		u=get(u); v=get(v);
		if (u==v) return 0;
		p[u]=v;
		return 1;
	}
};

ll check(vector<ll> incl, ll excl){
	DSU tr(n);
	vector<ll> checkarr;
	for (auto i:incl){
		if (i==excl) continue;
		checkarr.push_back(i);
		tr.unite(e[i].ff, e[i].ss); 
	}
	ll ret=INT_MAX;
	for (ll i=0; i<m; i++){
		if (i==excl) continue;
		if (tr.get(e[i].ff)!=tr.get(e[i].ss)){
			checkarr.push_back(i);
			ret=min(ret, count_common_roads(checkarr));
			checkarr.pop_back();
		}
	}
	// cout << "IDRequest: " << excl << ": " << ret << ln;
	// for (auto ch:checkarr) cout << ch << " ";
	// cout << ":: ";
	// ll ret=count_common_roads(checkarr);
	// cout << ret << ln;
	return ret;
}

vector<int> find_roads(int _n, vector<int> u, vector<int> v) {
	n=_n; m=u.size();
	e.resize(m); A.clear(); A.resize(n);
	for (ll i=0; i<m; i++){
		e[i]={u[i], v[i]};
		A[u[i]].push_back(i); A[v[i]].push_back(i);
	}
	isBridge.clear(); isBridge.resize(m);
	vector<ll> tin(n, -1), tmin(n, -1); ll timer=0;
	findBridge(0, 0, tin, tmin, timer);
	
	noroyal.clear(); noroyal.resize(m, 0);
	vector<ll> ans;
	vector<bool> vis(n); vector<ll> edges;
	// for (ll i=0; i<m; i++) cout << isBridge[i] << " ";
	// cout << ln; return ans;
	while (ans.size()==0){
		edges.clear(); vis.assign(n, 0);
		findST(0, vis, edges);
		// cout << "Request: ";
		// for (auto ch:edges) cout << ch << " ";
		// cout << ":: ";
		ll ret = count_common_roads(edges);
		// cout << ret << ln;
		if (ret==n-1){
			ans=edges; break;
		}
		for (auto i:edges){
			if (isBridge[i]) continue;
			ll nret=check(edges, i);
			if (nret>=ret){
				noroyal[i]=1;
			}
		}
	}
	return ans;
}

• Subtask 1: 0 / 13
• Subtask 2: 0 / 17
• Subtask 3: 0 / 21
• Subtask 4: 0 / 19
• Subtask 5: 0 / 30