Submission #478102

#	Time	Username	Problem	Language	Result	Execution time	Memory
478102		starplat	Islands (IOI08_islands)	C++14	24 / 100	1769 ms	131072 KiB

islands

#include <bits/stdc++.h>
#define int long long
using namespace std;
int n,v,w,vis[1000005],dist[1000005],path,ans;
vector<pair<int,int>> g[1000005];
vector<int> clr;
priority_queue<pair<int,int>> q;
void dij(int x)
{
	q.push({0,x});
	while (q.size()){
		v=q.top().second;
		q.pop();
		if (vis[v]) continue;
		vis[v]=1;
		clr.push_back(v);
		for (auto i:g[v]){
			if (vis[i.first]) continue;
			if (dist[i.first]<dist[v]+i.second){
				dist[i.first]=dist[v]+i.second;
				q.push({dist[i.first],i.first});
			}
		}
	}
}
signed main()
{
	cin>>n;
	for (int i=1;i<=n;i++){
		cin>>v>>w;
		g[i].push_back({v,w});
		g[v].push_back({i,w});
	}
	for (int i=1;i<=n;i++){
		if (!vis[i]) {
			dij(i);
			int mx=0,node=0;
			for (int i:clr) {
				if (dist[i]>mx) mx=dist[i],node=i;
				dist[i]=0,vis[i]=0;
			}
			//cout<<node<<" "<<mx<<"\n";
			path=0;
			dij(node);
			for (int i:clr) path=max(path,dist[i]);
			clr.clear();
			ans+=path;
			//cout<<path<<"\n";
		}
	}
	cout<<ans<<"\n";
}
//for each connected component find the tree diameter,and travel to next subgraph?
//dijstra with longest path?
//love to do graph questions, at the same time hate don't no how to solve graph questions

• 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