Submission #1127852

#	Time	Username	Problem	Language	Result	Execution time	Memory
1127852		czauderna	Duathlon (APIO18_duathlon)	C++20	0 / 100	45 ms	6212 KiB

count_triplets

// podzadanie na cykle i sciezki

#include <bits/stdc++.h>
using namespace std;
using ll=long long;
#define enl cerr<<'\n'
#define onl cout<<'\n'
#define sz(x) (int)(x).size()
#define rep(a, b) for(int a=0; a<(b); a++)
#define what(x) cerr<<(#x)<<": "<<(x)<<'\n'

constexpr int N=1e5+6;
vector<int> adj[N];
int gle[N];
bool used[N];
ll ans=0;

void bfs(int z) {
    queue<pair<int, int>> q;
    int d=1;
    used[z]=true;
    q.push({z, 1});
    while(!q.empty()) {
        auto [x, xd]=q.front();
        d=max(d, xd);
        q.pop();
        for(auto y:adj[x]) {
            if(!used[y]) {
                used[y]=true;
                q.push({y, xd+1});
            }
        }
    }
    ans+=1LL*d*(d-1)*(d-2)/3;
}

int main() {
    cin.tie(nullptr)->sync_with_stdio(false);
    int n,m;
    cin>>n>>m;
    rep(i, m) {
        int x,y;
        cin>>x>>y;
        adj[x].push_back(y);
        adj[y].push_back(x);
    }
    for(int i=1; i<=n; i++) {
        if(sz(adj[i])==1 && !used[i]) { // poczatek sciezki
            bfs(i);
        }
    }
    for(int i=1; i<=n; i++) {
        if(sz(adj[i])==2 && !used[i]) { // poczatek cyklu
            bfs(i);
        }
    }
    cout<<ans;onl;
}

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