Submission #277060

#	Time	Username	Problem	Language	Result	Execution time	Memory
277060		tinjyu	Duathlon (APIO18_duathlon)	C++14	0 / 100	1041 ms	1048580 KiB

count_triplets

#include <iostream>
using namespace std;
long long int son[1000005],ans,cnt,tmp[1000005],n,m,road[1000005],map[1000005][2];
void dfs(int x,int fa)
{
	son[x]=1;
	long long int g=road[x];
	while(g!=-1)
	{
		long long int now=map[g][0];
		if(now!=fa)
		{
			dfs(now,x);
			son[x]+=son[now];
		}
		g=map[g][1];
	}
	return ;
}
void find(int x,int fa)
{
	cnt=0;
	long long int g=road[x];
	while(g!=-1)
	{
		long long int now=map[g][0];
		if(now!=fa)
		{
			ans+=(n-son[now]-1)*son[now];
		}
		g=map[g][1];
	}
	ans+=(n-son[x])*(son[x]-1);
	g=road[x];
	while(g!=-1)
	{
		long long int now=map[g][0];
		if(now!=fa)
		{
			find(now,x);
		}
		g=map[g][1];
	}
	return ;
}
int main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++)road[i]=-1;
	for(int i=1;i<=m;i++)
	{
		int u,v;
		cin>>u>>v;
		map[i*2][0]=v;
		map[i*2][1]=road[u];
		road[u]=i*2;
		map[i*2+1][0]=i;
		map[i*2+1][1]=road[v];
		road[v]=i*2+1;
	}
	dfs(1,-1);
	find(1,-1);
	cout<<ans<<endl;
	return 0;
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 8
• Subtask 4: 0 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 15
• Subtask 7: 0 / 20
• Subtask 8: 0 / 8
• Subtask 9: 0 / 10