Submission #626026

#	Time	Username	Problem	Language	Result	Execution time	Memory
626026		Do_you_copy	Duathlon (APIO18_duathlon)	C++17	31 / 100	309 ms	38244 KiB

count_triplets

#include <bits/stdc++.h>
#define int long long
#define fi first
#define se second
#define pb push_back
#define faster ios_base::sync_with_stdio(0); cin.tie(0);
using namespace std;
using ll = long long;
using ull = unsigned ll;
using ld = long double;
using pii = pair <int, int>;
using pil = pair <int, ll>;
using pli = pair <ll, int>;
using pll = pair <ll, ll>;
mt19937 Rand(chrono::steady_clock::now().time_since_epoch().count());

ll min(const ll &a, const ll &b){
    return (a < b) ? a : b;
}

ll max(const ll &a, const ll &b){
    return (a > b) ? a : b;
}

//const ll Mod = 1000000007;
//const ll Mod2 = 999999999989;
//only use when required
const int maxN = 1e5 + 1;
int n, m;
int low[maxN];
int num[maxN];
bool onstack[maxN];
bool visited[maxN];
int timedfs;
int id[maxN];
int scc;
vector <vector <int>> adj;
vector <vector <int>> adj1;
vector <int> S;

void pre_dfs(int u, int p){
    low[u] = num[u] = ++timedfs;
    S.pb(u);
    onstack[u] = 1;
    visited[u] = 1;
    for (int i: adj[u]){
        if (i == p) continue;
        if (!visited[i]){
            pre_dfs(i, u);
            low[u] = min(low[u], low[i]);
        }
        else if(onstack[i]){
            low[u] = min(low[u], num[i]);
        }
    }
    if (low[u] == num[u]){
        ++scc;
        int v;
        do{
            v = S.back();
            S.pop_back();
            id[v] = scc;
            onstack[v] = 0;
        } while (v != u);
    }
}

map <pii, bool> mp;

ll ans = 0;
bool vis[maxN];
int sz[maxN];
ll sumsz[maxN];
ll child[maxN];
int totalsz;
inline ll calc(ll x){
    return x * (x - 1) * (x - 2);
}

inline ll cal(ll x){
    return x * x;
}

void dfs(int u){
    totalsz += sz[u];
    vis[u] = 1;
    for (int i: adj1[u]){
        if (vis[i]) continue;
        dfs(i);
        sumsz[u] += sumsz[i];
    }
    sumsz[u] += sz[u];
    ans += calc(sz[u]);
}

void dfs1(int u, int p){
    for (int i: adj1[u]){
        if (i == p) continue;
        dfs1(i, u);
        ans += child[u] * (child[i] + 1) * 2;
        child[u] += child[i] + 1;
        ans += 2 * sumsz[i] * cal(sz[u] - 1);
    }
    ans += 2 * (totalsz - sumsz[u]) * cal(sz[u] - 1);
    ans += 2 * (sumsz[u] - sz[u]) * (totalsz - sumsz[u]);
}

void Init(){
    cin >> n >> m;
    adj.resize(n + 1);
    for (int i = 1; i <= m; ++i){
        int u, v;
        cin >> u >> v;
        adj[u].pb(v);
        adj[v].pb(u);
    }
    for (int i = 1; i <= n; ++i){
        if (!visited[i]){
            pre_dfs(i, i);
        }
    }
    adj1.resize(scc + 1);
    for (int i = 1; i <= n; ++i){
        ++sz[id[i]];
        for (int j: adj[i]){
            if (id[i] != id[j] && !mp[{id[i], id[j]}]){
                mp[{id[i], id[j]}] = 1;
                mp[{id[j], id[i]}] = 1;
                adj1[id[i]].pb(id[j]);
                adj1[id[j]].pb(id[i]);
            }
        }
    }
    for (int i = 1; i <= scc; ++i){
        if (!vis[i]){
            totalsz = 0;
            dfs(i);
            dfs1(i, i);
        }
    }
    cout << ans;
}

#define debu
#define taskname "test"
signed main(){
    if (fopen(taskname".inp", "r")){
        freopen(taskname".inp", "r", stdin);
        #ifdef debug
        freopen(taskname".out", "w", stdout);
        #endif
    }
    faster;
    ll tt = 1;
    //cin >> tt;
    while (tt--){
        Init();
    }
    if (fopen("timeout.txt", "r")){
        ofstream timeout("timeout.txt");
        timeout << 1000 * double(clock()) / CLOCKS_PER_SEC;
        #ifndef debug
        cerr << "\nTime elapsed: " << 1000 * double(clock()) / CLOCKS_PER_SEC << "ms\n";
        #endif
    }
}

Compilation message (stderr)

count_triplets.cpp: In function 'int main()':
count_triplets.cpp:148:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  148 |         freopen(taskname".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

• 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