Submission #559808

#	Time	Username	Problem	Language	Result	Execution time	Memory
559808		hoanghq2004	Duathlon (APIO18_duathlon)	C++14	0 / 100	110 ms	22788 KiB

count_triplets

#include <bits/stdc++.h>
#pragma GCC optimize ("O3")
#pragma GCC optimize ("unroll-loops")
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
using namespace std;

template <typename T>
using ordered_set = tree <T, null_type, less <T>, rb_tree_tag, tree_order_statistics_node_update>;

const int N = 1e5 + 10;

int n, m;
vector <int> e[N], g[N];
vector <int> stk;
int num[N], low[N], ti, cnt, comp[N], a[N], sz[N];
long long ans;

void dfs(int u, int p) {
    num[u] = low[u] = ++ti;
    stk.push_back(u);
    for (auto v: g[u]) {
        if (v == p) continue;
        if (!num[v]) {
            dfs(v, u);
            low[u] = min(low[u], low[v]);
        } else low[u] = min(low[u], num[v]);
    }
    if (low[u] != num[u]) return;
    ++cnt;
    while (1) {
        int v = stk.back();
        stk.pop_back();
        comp[v] = cnt;
        ++a[cnt];
        if (u == v) break;
    }
}

void solve(int u, int p) {
    sz[u] = a[u];
    for (auto v: e[u]) {
        if (v == p) continue;
        solve(v, u);
        sz[u] += sz[v];
    }
    int cur = n - sz[u];
    for (auto v: e[u]) {
        if (v == p) continue;
        ans += 2LL * sz[v] * cur * a[u];
        cur += sz[v];
    }
    ans += 2LL * (n - sz[u]) * (a[u] - 1) * (a[u] - 1);
    for (auto v: e[u]) {
        if (v == p) continue;
        ans += 2LL * sz[v] * (a[u] - 1) * (a[u] - 1);
    }
    ans += a[u] * (a[u] - 1) * (a[u] - 2);
}

int main() {
    ios :: sync_with_stdio(0); cin.tie(0);
    cin >> n >> m;
    while (m--) {
        int u, v;
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    dfs(1, 0);
    for (int u = 1; u <= n; ++u) assert(num[u]);
    for (int u = 1; u <= n; ++u)
        for (auto v: g[u])
            if (comp[u] != comp[v])
                e[comp[u]].push_back(comp[v]);
    solve(1, 0);
    cout << ans;
}

• 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