Submission #982210

#	Time	Username	Problem	Language	Result	Execution time	Memory
982210		Faisal_Saqib	Duathlon (APIO18_duathlon)	C++17	23 / 100	1056 ms	1048576 KiB

count_triplets

#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int N=1e5+10;
vector<int> ma[N];
bool vis[N];
ll ans=0,sz[N],dp[N],dp_[N];
void dfs(int x,int p=-1)
{
	sz[x]=1;
	vis[x]=1;
	for(auto y:ma[x])
	{
		if(y!=p)
		{
			dfs(y,x);
			sz[x]+=sz[y];
			dp[x]-=(sz[y]*sz[y]);
		}
	}
	dp[x]+=((sz[x]-1)*(sz[x]-1));
}
void ChangeRoot(int x,int y)
{
	// 
	dp[x]+=(sz[y]*sz[y]);
	dp[x]-=((sz[x]-1)*(sz[x]-1));
	dp[y]-=((sz[y]-1)*(sz[y]-1));
	sz[x]-=sz[y];
	sz[y]+=sz[x];
	dp[x]+=((sz[x]-1)*(sz[x]-1));
	dp[y]+=((sz[y]-1)*(sz[y]-1));
	dp[y]-=(sz[x]*sz[x]);
}
void dfs_(int x,int p=-1)
{
	vis[x]=1;
	ans+=dp[x];
	for(auto y:ma[x])
	{
		if(y!=p)
		{			
			ChangeRoot(x,y);
			dfs_(y,x);
			ChangeRoot(y,x);
		}
	}
}
void solve()
{
	int n,m;
	cin>>n>>m;
	for(int j=0;j<m;j++)
	{
		int x,y;
		cin>>x>>y;
		ma[x].push_back(y);
		ma[y].push_back(x);
	}
	for(int i=1;i<=n;i++)
	{
		if(!vis[i])
		{
			dfs(i);
		}
	}
	for(int i=1;i<=n;i++)
		vis[i]=0;
	for(int i=1;i<=n;i++)
	{
		if(!vis[i])
		{
			dfs_(i);
		}
	}
	cout<<ans<<endl;
}
int main()
{
  cin.tie(0);
  cout.tie(0);
  ios::sync_with_stdio(0);
	solve();
}

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