Submission #216360

#	Time	Username	Problem	Language	Result	Execution time	Memory
216360		theStaticMind	Duathlon (APIO18_duathlon)	C++14	31 / 100	924 ms	1048580 KiB

count_triplets

#include<bits/stdc++.h>
#define pb push_back
#define ii pair<int,int>
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define INF 100000000000000000
#define modulo 1000000007
#define mod 998244353
#define int long long int
using namespace std;

vector<int> adj[300005];
vector<int> sub(300005, 0);
vector<bool> vis(300005, false);
vector<bool> mark(300005, false);
int ans = 0;

void dfs(int x, int pre){
	sub[x] = 1;
	vis[x] = true;
	for(auto y : adj[x]){
		if(y == pre) continue;
		if(vis[y]){
			mark[y] = true;
			continue;
		}
		dfs(y, x);
		sub[x] += sub[y];
	}
}

void calc(int x, int pre, int sum){
	ans += 2ll * (sub[x] - 1) * (sum - sub[x]);

	int w = 0;

	for(auto y : adj[x]){
		if(y == pre) continue;
		ans += 2ll * sub[y] * w;
		w += sub[y];
	}

	for(auto y : adj[x]){
		if(y == pre) continue;
		calc(y, x, sum);
	}
}

int32_t main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	
	int n, m;
	cin >> n >> m;

	for(int i = 0; i < m; i++){
		int x, y;
		cin >> x >> y;
		adj[x].pb(y);
		adj[y].pb(x);
	}

	vector<int> root;
	for(int i = 1; i <= n; i++){
		if(sub[i] == 0) dfs(i, -1), root.pb(i);
	}
	for(auto r : root){ 
		if(!mark[r]) calc(r, -1, sub[r]);
		else ans += sub[r] * (sub[r] - 1) * (sub[r] - 2);
	}

	cout << ans;
}

• 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