Submission #408585

#	Time	Username	Problem	Language	Result	Execution time	Memory
408585		talant117408	Duathlon (APIO18_duathlon)	C++17	100 / 100	145 ms	28992 KiB

count_triplets

/*
    Code written by Talant I.D.
*/
 
#include <bits/stdc++.h>
//~ #include <ext/pb_ds/assoc_container.hpp>
 
//~ using namespace __gnu_pbds;
using namespace std;
 
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
//~ typedef tree <int, null_type, less <int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
 
#define precision(n) fixed << setprecision(n)
#define pb push_back
#define ub upper_bound
#define lb lower_bound
#define mp make_pair
#define eps (double)1e-9
#define PI 2*acos(0.0)
//~ #define endl "\n"
#define sz(v) int((v).size())
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
#define do_not_disturb ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define OK cout << "OK" << endl;
 
const int mod = 1e9+7;
 
ll mode(ll a) {
    while (a < 0) {
        a += mod;
    }
    return a % mod;
}
 
ll subt(ll a, ll b) {
    return mode(mode(a)-mode(b));
}
 
ll add(ll a, ll b) {
    return mode(mode(a)+mode(b));
}
 
ll mult(ll a, ll b) {
    return mode(mode(a)*mode(b));
}
 
ll binpow(ll a, ll b) {
    ll res = 1;
    while (b) {
        if (b&1) res = mult(res, a);
        a = mult(a, a);
        b >>= 1;
    }
    return res;
}

const int MAXN = 1e5+7;
vector <int> graph[MAXN], comps_graph[MAXN * 2], stacc;
int timer, fup[MAXN], tin[MAXN], compsn = 1;
ll ans, subtree[MAXN * 2], N;
ll n, m;

void find_artpoints(int v, int p = 0) {
    tin[v] = fup[v] = ++timer;
    stacc.pb(v);
    N++;
    for (auto to : graph[v]) {
        if (to == p) {
            continue;
        }
        if (tin[to]) {
            fup[v] = min(fup[v], tin[to]);
        }
        else {
            find_artpoints(to, v);
            fup[v] = min(fup[v], fup[to]);
            if (fup[to] >= tin[v]) {
                comps_graph[v].pb(n + compsn);
                while (!sz(comps_graph[n + compsn]) || comps_graph[n + compsn].back() != to) {
                    comps_graph[n + compsn].pb(stacc.back());
                    stacc.pop_back();
                }
                compsn++;
            }
        }
    }
}

void dfs2(int v, int p = -1) {
    subtree[v] = (v <= n);
    for (auto to : comps_graph[v]) {
        dfs2(to, v);
        subtree[v] += subtree[to];
        if (v > n) {
            ans -= 1ll * sz(comps_graph[v]) * subtree[to] * (subtree[to] - 1);
        }
    }
    if (v > n) {
        ans -= 1ll * sz(comps_graph[v]) * (N - subtree[v]) * (N - subtree[v] - 1);
    }
}

int main() {
    do_not_disturb
    
    cin >> n >> m;
    for (int i = 0; i < m; i++) {
        int x, y;
        cin >> x >> y;
        graph[x].pb(y);
        graph[y].pb(x);
    }
    
    for (int i = 1; i <= n; i++) {
        if (!tin[i]) {
            N = 0;
            find_artpoints(i);
            ans += 1ll * N * (N - 1) * (N - 2);
            dfs2(i);
        }
    }
    
    cout << ans;
    
    return 0;
}

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