Submission #260905

#	Time	Username	Problem	Language	Result	Execution time	Memory
260905		SorahISA	Duathlon (APIO18_duathlon)	C++17	0 / 100	1097 ms	1048580 KiB

count_triplets

#pragma GCC optimize("Ofast", "unroll-loops")
#include <bits/stdc++.h>
using namespace std;

#define int long long
#define double long double
using pii = pair<int, int>;
template<typename T>
using prior = priority_queue<T, vector<T>, greater<T>>;
template<typename T>
using Prior = priority_queue<T>;

#define X first
#define Y second
#define ALL(x) (x).begin(), (x).end()
#define eb emplace_back
#define pb push_back
#define fastIO() ios_base::sync_with_stdio(false), cin.tie(0)

const int maxn = 1E5 + 5;

int ans = 0;
vector<int> adj[maxn], vis(maxn), sz(maxn, 1);

void dfs(int now, int lst) {
    vis[now] = 1;
    for (auto x : adj[now]) {
        if (x != lst) dfs(x, now), sz[now] += sz[x];
    }
}

void dfs2(int now, int lst, int rt) {
    for (auto x : adj[now]) {
        if (x == lst) continue;
        ans += sz[x] * (sz[rt] - sz[x] - 1);
        dfs2(x, now, rt);
    }
}

int32_t main() {
    fastIO();
    
    int n, m;
    cin >> n >> m;
    
    for (int i = 0; i < m; ++i) {
        int u, v;
        cin >> u >> v;
        adj[u].eb(v), adj[v].eb(u);
    }
    
    for (int i = 1; i <= n; ++i) {
        if (!vis[i]) {
            dfs(i, -1), dfs2(i, -1, i);
        }
    }
    
    cout << ans << "\n";
    
    return 0;
}

• 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