제출 #259167

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
259167		_7_7_	Duathlon (APIO18_duathlon)	C++14	23 / 100	652 ms	1048580 KiB

count_triplets

#include <bits/stdc++.h>                                           
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
 
using namespace std;
using namespace __gnu_pbds;
 
#define int long long
//#pragma GCC optimize("Ofast")
//#pragma comment(linker, "/stack:200000000")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4")
 
 
#define file(s) freopen(s".in","r",stdin); freopen(s".out","w",stdout);
#define fastio ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
#define all(x) x.begin(), x.end()
#define sz(s) (int)s.size()
#define pb push_back
#define ppb pop_back
#define mp make_pair
#define s second
#define f first
 
 
 
 
typedef pair < long long, long long > pll;    
typedef pair < int, int > pii;  
typedef unsigned long long ull;         
typedef vector < pii > vpii;                                   	
typedef vector < int > vi;
typedef long double ldb;  
typedef long long ll;  
typedef double db;
 
typedef tree < int, null_type, less < int >, rb_tree_tag, tree_order_statistics_node_update > ordered_set;
 
const int inf = 1e9, maxn = 2e5 + 48, mod = 998244353, N = 1e5 + 12;
const int dx[] = {1, -1, 0, 0}, dy[] = {0, 0, 1, -1}, block = 300;
const pii base = mp(1171, 3307), Mod = mp(1e9 + 7, 1e9 + 9);
const db eps = 1e-12, pi = acos(-1);
const ll INF = 1e18;
 
int n, m, v, u, cnt[N], p[N], col[N], Sz[N], Cnt[N], par[N];
int tin[N], tout[N], timer, d[N], ans, k;
bool was[N];
vi g[N];

bool upper (int v, int u) {
	return tin[v] <= tin[u] && tout[v] >= tout[u];
}

int get (int v) {
	return v == p[v] ? v :  p[v] = get(p[v]);
}


void merge (int v, int u) {
	v = get(v), u = get(u);
	if (v == u)
		return;

	if (Cnt[v] < Cnt[u])
		swap(v, u);

	p[u] = v;
	Cnt[v] += Cnt[u];
}


void dfs (int v, int p = 0) {
	par[v] = p;
	tin[v] = ++timer;
	cnt[v] = 1;
	col[v] = k;
	++Sz[k];

	for (auto to : g[v])
		if (!col[to]) {
			dfs(to, v);
			cnt[v] += cnt[to];
		}

	tout[v] = timer;
} 

int V;
void dfs1 (int v, int u) {
	for (auto to : g[v])
		if (to != par[v] && upper(to, u)) {			
			if ((V == v && to == u) || (to == V && v == u))
				continue;
			dfs1(to, u); 
			d[v] = d[to] + 1;
			merge(v, to);
		}
}

void dfs2 (int v) {
    was[v] = 1;
	for (auto to : g[v])
		if (to != par[v]) {
			if (upper(to, v)) {
				V = to;
				dfs1(to, v);
			} else if (!was[to])
				dfs2(to);
		}
}

 
main () {
	fastio
	cin >> n >> m;
	while (m--) {
		cin >> v >> u;
		g[v].pb(u);
		g[u].pb(v);
	}

	for (int i = 1; i <= n; ++i) {
	    p[i] = i;
		Cnt[i] = 1;

		if (!col[i]) {
		    ++k;
			dfs(i); 
			ans += Sz[k] * (Sz[k] - 1) * (Sz[k] - 2);
		}
	}


	for (int i = 1; i <= n; ++i)
		if (!was[i])
			dfs2(i);
	

	for (int i = 1; i <= n; ++i) {
		for (auto j : g[i])
			if (j != par[i])
				ans -= cnt[j] * (cnt[j] - 1);

		ans -= (Sz[col[i]] - cnt[i]) * (Sz[col[i]] - cnt[i] - 1);

//	    cerr << i << ' ' << d[i] << endl;
		ans += d[i] * (d[i] - 1);
		ans += (Cnt[get(i)] - d[i] - 1) * (Cnt[get(i)] - d[i] - 2);
	}
	
	
	cout << ans << endl;
}                    

컴파일 시 표준 에러 (stderr) 메시지

count_triplets.cpp:112:7: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main () {
       ^

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