Submission #1021737

#	Time	Username	Problem	Language	Result	Execution time	Memory
1021737		ByeWorld	Duathlon (APIO18_duathlon)	C++14	31 / 100	123 ms	27732 KiB

count_triplets

#include <bits/stdc++.h>
// #pragma GCC optimize("O3", "unroll-loops")
#define ll long long
#define int long long
#define pb push_back
#define fi first
#define se second
#define lf (id<<1)
#define rg ((id<<1)|1)
#define md ((l+r)>>1)
#define ld long double
using namespace std;
typedef pair<int,int> pii;
typedef pair<pii, int> ipii;
const int MAXN = 1e5+10;
const int MAXA = 9e3+20;
const ll INF = 1e18+10;
const int LOG = 20;
const int SQRT = 450;
const vector<int> NOL = {};
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const vector<int> dx = {1, -1, 0, 0};
const vector<int> dy = {0, 0, 1, -1};
const int MOD = 1e9+7;
void chmx(int &a, int b){ a = max(a, b); }
int sum(int a, int b){ return (a+b)%MOD; }
int mul(int a, int b){ return (a*b)%MOD; }
void chsum(int &a, int b){ a = sum(a,b); }

int n, m;
int u[MAXN], v[MAXN];
vector <int> adj[MAXN];
int disc[MAXN], low[MAXN], tim;
int ap[MAXN], color, col[MAXN];
vector <int> edge[MAXN];
int sub[MAXN], val[MAXN];

void dfs(int nw, int par){
	disc[nw] = low[nw] = ++tim;
	for(auto nx : adj[nw]){
		if(nx==par) continue;
		if(disc[nx]!=0) low[nw] = min(low[nw], disc[nx]);
		else {
			dfs(nx, nw);
			low[nw] = min(low[nw], low[nx]);
		}
	}
	if(disc[nw]==low[nw] || (adj[nw].size()>=2 && nw==1)){
		ap[nw] = 1; col[nw] = ++color; val[col[nw]] = 1;
	}
}
void COL(int nw, int ty){
	col[nw] = ty; val[ty]++;
	for(auto nx : adj[nw]){
		if(ap[nx] || col[nx]) continue;
		COL(nx, ty);
	}
}

int ANS, root[MAXN];
void trav(int nw, int par, int roo){
	//S - C - F
	int te = 0, bef = 0; root[nw] = roo;
	sub[nw] = val[nw];
	for(auto nx : edge[nw]){
		if(nx==par) continue;
		trav(nx, nw, roo);
		sub[nw] += sub[nx];
		te += bef*sub[nx]*2;
		bef += sub[nx];
	}
	ANS += te*val[nw];
}
void bd(int nw, int par){
	for(auto nx : edge[nw]){
		if(nx==par) continue;
		bd(nx, nw);
	}
	int up = sub[root[nw]]-sub[nw], dw = sub[nw]-val[nw];
	int te = up*dw*2;
	// cout << nw << ' ' << te << " te\n";
	ANS += te*val[nw];
}
signed main(){
	// ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	cin >> n >> m;
	for(int i=1; i<=m; i++){
		cin >> u[i] >> v[i];
		adj[u[i]].pb(v[i]); adj[v[i]].pb(u[i]);
	}
	for(int i=1; i<=n; i++)
		if(!disc[i]) dfs(i, 0);
	for(int i=1; i<=n; i++){
		if(!col[i]) COL(i, ++color);
	}
	for(int i=1; i<=m; i++){
		int x = col[u[i]], y = col[v[i]];
		if(x==y) continue;
		edge[x].pb(y); edge[y].pb(x);
	}
	for(int i=1; i<=color; i++){
		sort(edge[i].begin(), edge[i].end());
		edge[i].resize(unique(edge[i].begin(), edge[i].end()) - edge[i].begin());
		// for(auto in : edge[i]) cout << in << ' ';
		// 	cout << i << "i\n";
	}
	for(int i=1; i<=n; i++)
		if(!sub[i]){ trav(i, 0, i); bd(i, 0); }
	// SCF
	for(int i=1; i<=color; i++){
		if(val[i]>=3) ANS += val[i]*(val[i]-1)*(val[i]-2);
	}
	// SC-F atau S-CF
	for(int i=1; i<=color; i++){
		if(val[i]>=2){
			int siz = sub[root[i]];
			ANS += val[i]*(val[i]-1)*(siz-val[i])*2;

			int oth = 0; // C - SF
			for(auto nx : edge[i]){
				oth += val[nx];
			}
			ANS += val[i]*(val[i]-1)*oth;
		}
	}
	// for(int i=1; i<=color; i++){
	// 	cout << i << ' ' << val[i] << " val\n";
	// }

	cout << ANS << '\n';
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 8 / 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