Submission #49245

#	Time	Username	Problem	Language	Result	Execution time	Memory
49245		BThero	Duathlon (APIO18_duathlon)	C++17	25 / 100	1064 ms	19540 KiB

count_triplets

// Why am I so stupid? :c
#include <bits/stdc++.h>

#define pb push_back
#define mp make_pair

#define all(x) (x).begin(), (x).end()

#define fi first
#define se second

typedef long long ll;

using namespace std;

struct edge {
    int u, v;

    edge() {
        u = v = 0;
    }
} e[200005];

int tin[100005], fup[100005];

vector <int> adj[100005];

vector <int> cp[100005];

bool bad[200005];

int col[100005];

bool u[200005];

int timer, sz;

int n, m;

ll ans;

void dfs(int v, int pr) {
    tin[v] = fup[v] = ++timer;
    u[v] = 1;

    for (int id : adj[v]) {
        int to;

        if (v == e[id].u) {
            to = e[id].v;
        }
        else {
            to = e[id].u;
        }

        if (to == pr) {
            continue;
        }

        if (u[to]) {
            fup[v] = min(fup[v], tin[to]);
        }
        else {
            dfs(to, v);
            fup[v] = min(fup[v], fup[to]);

            if (fup[to] > tin[v]) {
                bad[id] = 1;
            }
        }
    }
}

void dfs2(int v) {
    cp[sz].pb(v);
    u[v] = 1;

    for (int to : adj[v]) {
        if (u[to]) {
            continue;
        }

        dfs2(to);
    }
}

void calc(int v, int st, int mlt, int cur) {
    if (st != v) {
        int a = cp[st].size();
        int b = cp[v].size();

        ans += 1ll * (a - 1) * (b - 1) * (mlt + a - 1 + b - 1);
        ans += 1ll * (b - 1) * (mlt + b - 1);
        ans += 1ll * (a - 1) * (mlt + a - 1);
        ans += 1ll * mlt;
    }

    u[v] = 1;

    for (int id : adj[v]) {
        bool good = 1;
        int to, nxt;

        if (col[e[id].v] == v) {
            if (e[id].v == cur || cur == -1) {
                good = 0;
            }

            nxt = e[id].u;
        }
        else {
            if (e[id].u == cur || cur == -1) {
                good = 0;
            }

            nxt = e[id].v;
        }

        to = col[nxt];

        if (u[to]) {
            continue;
        }

        calc(to, st, mlt + 1 + good * (cp[v].size() - 1), nxt);
    }
}

ll f(ll x) {
    return x * (x - 1) * (x - 2);
}

void solve() {
    scanf("%d %d", &n, &m);

    for (int i = 1; i <= m; ++i) {
        scanf("%d %d", &e[i].u, &e[i].v);

        adj[e[i].u].pb(i);
        adj[e[i].v].pb(i);
    }

    for (int i = 1; i <= n; ++i) {
        if (u[i]) {
            continue;
        }

        dfs(i, -1);
    }

    for (int i = 1; i <= n; ++i) {
        adj[i].clear();
        u[i] = 0;
    }

    for (int i = 1; i <= m; ++i) {
        if (!bad[i]) {
            adj[e[i].u].pb(e[i].v);
            adj[e[i].v].pb(e[i].u);
        }
    }

    for (int i = 1; i <= n; ++i) {
        if (u[i]) {
            continue;
        }

        ++sz; dfs2(i);

        for (int it : cp[sz]) {
            col[it] = sz;
        }
    }

    for (int i = 1; i <= n; ++i) {
        adj[i].clear();
        u[i] = 0;
    }

    for (int i = 1; i <= m; ++i) {
        if (bad[i]) {
            adj[col[e[i].v]].pb(i);
            adj[col[e[i].u]].pb(i);
        }
    }

    for (int i = 1; i <= sz; ++i) {
        ans += f(cp[i].size());

        for (int j = 1; j <= sz; ++j) {
            u[j] = 0;
        }

        calc(i, i, -1, -1);
    }

    printf("%lld\n", ans);
}

int main() {
#ifdef BThero
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif // BThero

    int tt = 1;

    while (tt--) {
        solve();
    }

    return 0;
}

Compilation message (stderr)

count_triplets.cpp: In function 'void solve()':
count_triplets.cpp:134:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &n, &m);
     ~~~~~^~~~~~~~~~~~~~~~~
count_triplets.cpp:137:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d", &e[i].u, &e[i].v);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

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