Submission #1062404

#	Time	Username	Problem	Language	Result	Execution time	Memory
1062404		tamir1	Islands (IOI08_islands)	C++17	24 / 100	207 ms	131072 KiB

islands

#include<bits/stdc++.h>
#define ll long long
#define ff first
#define ss second
using namespace std;
int n,x,p;
vector<pair<int,ll>> v[1000002];
vector<int> com[1000001];
ll ans,l,dis[1000001];
bitset<1000001> ok;
priority_queue<pair<ll,int>> q;
void dfs(int x){
	if(ok[x]) return;
	ok[x]=1;
	com[p].push_back(x);
	for(pair<int,ll> i:v[x]){
		dfs(i.ff);
	}
}
void dijk(){
	while(!q.empty()){
		ll d=q.top().ff;
		int x=q.top().ss;
		q.pop();
		if(ok[x]) continue;
		ok[x]=1;
		dis[x]=d;
		for(pair<int,ll> i:v[x]){
			if(!ok[i.ff]) q.push({d+i.ss,i.ff});
		}
	}
}
ll solve(int p){
	q.push({0,com[p][0]});
	dijk();
	ll mx=0;
	int x;
	for(int i:com[p]){
		if(mx<dis[i]){
			x=i;
			mx=dis[i];
		}
		dis[i]=0;
		ok[i]=0;
	}
	q.push({0,x});
	dijk();
	mx=0;
	for(int i:com[p]){
		mx=max(dis[i],mx);
	}
	//cout << mx << "\n";
	return mx;
}
int main(){
	ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	cin >> n;
	for(int i=1;i<=n;i++){
		cin >> x >> l;
		v[i].push_back({x,l});
		v[x].push_back({i,l});
	}
	for(int i=1;i<=n;i++){
		if(!ok[i]){
			p++;
			dfs(i);
		}
	}
	ok.reset();
	for(int i=1;i<=p;i++) ans+=solve(i);
	cout << ans;
}

• Subtask 1: 24 / 33
• Subtask 2: 0 / 3
• Subtask 3: 0 / 4
• Subtask 4: 0 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10