제출 #408931

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
408931		Jasiekstrz	Islands (IOI08_islands)	C++17	100 / 100	1059 ms	131072 KiB

islands

#include<bits/stdc++.h>
#define fi first
#define se second
using namespace std;
const int N=1e6;
vector<int> e[N+10];
int f[N+10];
int l[N+10];
bitset<N+10> vis_fill;
bitset<N+10> vis_s;
bitset<N+10> on_cycle;
vector<int> t;
void dfs_fill(int x)
{
	t.push_back(x);
	vis_fill[x]=true;
	for(int &v:e[x])
	{
		if(!vis_fill[v])
			dfs_fill(v);
	}
	return;
}
long long aa;
long long dfs_tree(int x)
{
	on_cycle[x]=true;
	long long ans=0;
	for(int &v:e[x])
	{
		if(on_cycle[v])
			continue;
		long long tmp=dfs_tree(v);
		aa=max(aa,ans+tmp+(v==f[x] ? l[x]:l[v]));
		ans=max(ans,tmp+(v==f[x] ? l[x]:l[v]));
	}
	return ans;
}
int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	int n;
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>f[i]>>l[i];
		e[i].push_back(f[i]);
		e[f[i]].push_back(i);
	}
	long long ans=0;
	for(int j=1;j<=n;j++)
	{
		if(!vis_fill[j])
		{
			t.clear();
			dfs_fill(j);
			long long ans_s=0;
			int c;
			for(int i=t[0];true;i=f[i])
			{
				if(vis_s[i])
				{
					c=i;
					break;
				}
				vis_s[i]=true;
			}
			long long l_all=l[c];
			on_cycle[c]=true;
			for(int i=f[c];i!=c;l_all+=l[i],i=f[i])
				on_cycle[i]=true;
			long long mx=0,mn=0;
			int x=c;
			do{
				x=f[x];
				aa=0;
				long long ww=dfs_tree(x);
				ans_s=max(ans_s,aa);
				ans_s=max({ans_s,mx+ww,mn+ww});
				mx=max(mx,ww)+l[x];
				mn=max(mn,ww+l_all)-l[x];
			}while(x!=c);
			ans+=ans_s;
		}
	}
	cout<<ans<<"\n";
	return 0;
}

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