Submission #136251

#	Time	Username	Problem	Language	Result	Execution time	Memory
136251		baluteshih	Duathlon (APIO18_duathlon)	C++14	100 / 100	191 ms	27656 KiB

count_triplets

#include <bits/stdc++.h>
#define jizz ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#define pb push_back
#define ET cout << "\n"
#define F first
#define S second
#define MP make_pair
#define MEM(i,j) memset(i,j,sizeof i)
#define ALL(v) v.begin(),v.end()
#define DB(a,s,e) {for(int i=s;i<e;++i) cout << a[i] << " ";ET;};
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

vector<ll> G[100005],BG[100005];
ll low[100005],dfn[100005],comp[100005],req[100005],avsub[100005],sub[100005],dft;
ll ans1,ans2,c;
stack<ll> st;
bitset<100005> vis;

void con(int u)
{
	vis[u]=1,++c;
	for(ll i:G[u])
		if(!vis[i])
			con(i);
}

void dfs(int u,int f)
{
	ll usq=0;
	low[u]=dfn[u]=++dft,sub[u]=1,comp[u]=c,avsub[u]=1;
	st.push(u);
	for(ll i:G[u])
		if(i!=f)
			if(!dfn[i])
			{
				dfs(i,u),sub[u]+=sub[i];
				if(low[i]>=dfn[u])
				{
					ll sq=0;
					vector<ll> v;
					avsub[u]+=sub[i];
					for(int x=-1;x!=i;)
					{
						x=st.top(),st.pop();
						sq+=avsub[x]*avsub[x];
						v.pb(x);
					}
					for(ll j:v)
						req[j]+=(c-sub[i])*(c-sub[i])+sq-avsub[j]*avsub[j];
					req[u]+=sq;
				}
				else
					low[u]=min(low[u],low[i]);
			}
			else if(dfn[u]>dfn[i])
				low[u]=min(low[u],dfn[i]);
}


int main()
{jizz
	ll m,a,b,n,ans=0;
	cin >> n >> m;
	while(m--)
		cin >> a >> b,G[a].pb(b),G[b].pb(a);
	for(int i=1;i<=n;++i)
		if(!vis[i])
			c=0,con(i),dfs(i,i);
	for(int i=1;i<=n;++i)
		ans+=(comp[i]-1)*(comp[i]-1)-req[i];
	cout << ans << "\n";
}

Compilation message (stderr)

count_triplets.cpp: In function 'void dfs(int, int)':
count_triplets.cpp:36:5: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
   if(i!=f)
     ^
count_triplets.cpp:32:5: warning: unused variable 'usq' [-Wunused-variable]
  ll usq=0;
     ^~~

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