Submission #849043

#	Time	Username	Problem	Language	Result	Execution time	Memory
849043		hngwlog	Duathlon (APIO18_duathlon)	C++14	36 / 100	59 ms	24272 KiB

count_triplets

#include <bits/stdc++.h>
using namespace std;

#define fi first
#define se second
#define _size(x) (int)x.size()
#define BIT(i, x) ((x >> i) & 1)
#define MASK(n) ((1 << n) - 1)
#define REP(i, n) for (int i = 0, _n = (n); i < _n; i++)
#define FOR(i, a, b) for (int i = a, _b = (b); i <= _b; i++)
#define FORD(i, a, b) for (int i = a, _b = (b); i >= _b; i--)
#define FORB1(i, mask) for (int i = mask; i > 0; i ^= i & - i)
#define FORB0(i, n, mask) for (int i = ((1 << n) - 1) ^ mask; i > 0; i ^= i & - i)
#define FORALL(i, a) for (auto i: a)
#define fastio ios_base::sync_with_stdio(0); cin.tie(0);

int n, m;
vector<vector<int>> adj;

namespace subtask1 {

    void main() {

        vector<vector<vector<int>>> f(n + 1, vector<vector<int>>(n + 1, vector<int>(n + 1)));
        FOR(i, 1, n) {
            vector<vector<int>> g((1 << n), vector<int>(n));
            FORALL(j, adj[i]) {
                if (j == i) continue;
                g[(1 << (i - 1)) | (1 << (j - 1))][j - 1] = 1;
            }
            FOR(mask, 0, MASK(n)) {
                FORB1(_mask, mask) {
                    int u = __builtin_ctz(_mask);
                    if (!g[mask][u]) continue;
                    FORB1(__mask, mask) {
                        int v = __builtin_ctz(__mask);
                        if (i == u + 1 || i == v + 1 || u == v) continue;
                        f[i][v + 1][u + 1]++;
                    }
                    FORALL(v, adj[u + 1]) {
                        if (BIT(v - 1, mask)) continue;
                        g[mask | (1 << (v - 1))][v - 1] = 1;
                    }
                }
            }
        }
        int ans = 0;
        FOR(i, 1, n) FOR(j, 1, n) FOR(z, 1, n) {
            if (i == j || i == z || j == z) continue;
            ans += (f[i][j][z] > 0);
        }
        cout << ans << '\n';
    }
}

namespace subtask2 {

    void main() {


    }
}

bool checkSub3() {

    vector<int> deg(n + 1);
    FOR(u, 1, n) FORALL(v, adj[u]) deg[v]++;
    FOR(u, 1, n) if (deg[u] > 2) return false;
    return true;
}


namespace subtask3 {

    const int inf = 1e9;

    int t_time = 0;
    vector<int> num, low, child, depth, vtx, sz;
    vector<vector<int>> p;

    void dfs(int _p, int u) {

        vtx.push_back(u);
        num[u] = ++t_time;
        low[u] = inf;
        FORALL(v, adj[u]) {
            if (v == _p) continue;
            if (num[v]) low[u] = min(low[u], num[v]);
            else {
                depth[v] = depth[u] + 1;
                p[0][v] = u;
                dfs(u, v);
                low[u] = min(low[u], low[v]);
                child[u] += child[v];
            }
        }
    }

    int jump(int u, int l) {

        FORB1(mask, l) u = p[__builtin_ctz(mask)][u];
        return u;
    }

    void main() {

        num.resize(n + 1);
        low.resize(n + 1);
        child.assign(n + 1, 1);
        sz.resize(n + 1);
        depth.resize(n + 1);
        p.assign(20, vector<int>(n + 1));
        long long ans = 0;
        FOR(u, 1, n) {
            if (num[u]) continue;
            vtx.clear();
            dfs(u, u);
            int cnt = _size(vtx);
            if (low[u] == inf) ans += 1LL * cnt * (cnt - 1) * (cnt - 2);
            else ans += 1LL * cnt * (cnt - 1) * (cnt - 2);
            FORALL(v, vtx) sz[v] = cnt;
        }
        FOR(j, 1, 19) FOR(i, 1, n) p[j][i] = p[j - 1][p[j - 1][i]];
        vector<int> f(n + 1);
        FOR(u, 1, n) {
            if (!p[0][u]) continue;
            if (low[u] < num[p[0][u]]) f[p[0][u]] += child[u];
        }
        FOR(u, 1, n) {
            if (low[u] != inf) continue;
            FORALL(v, adj[u]) {
                if (depth[u] > depth[v]) {
                    int value = sz[u] - child[u] + f[u];
                    ans -= 1LL * value * (value - 1);
                }
                else {
                    int r = jump(v, depth[u] - depth[v] - 1);
                    int value = child[r];
                    if (low[r] < num[u]) value += sz[u] - child[u];
                    ans -= 1LL * value * (value - 1);
                }
            }
        }
        cout << ans << '\n';
    }
}

vector<int> vis_check;

int dfs_check(int p, int u) {

    int res = 1;
    vis_check[u]++;
    FORALL(v, adj[u]) {
        if (v == p) continue;
        if (vis_check[v]) return 0;
        res = min(res, dfs_check(u, v));
    }
    return res;
}

bool checkSub45() {

    vis_check.resize(n + 1);
    int res = 1;
    FOR(u, 1, n) if (!vis_check[u]) res = min(res, dfs_check(- 1, u));
    if (res) return true;
    return false;
}

namespace subtask4 {

    vector<int> vis, child;
    vector<vector<int>> a;

    void dfs(int p, int u) {

        a[p][u]++;
        vis[u]++;
        FORALL(v, adj[u]) {
            if (vis[v]) continue;
            dfs(p, v);
            child[u] += child[v];
        }
    }

    void main() {

        a.assign(n + 1, vector<int>(n + 1));
        vis.resize(n + 1);
        child.resize(n + 1);
        int ans = 0;
        FOR(u, 1, n) {
            FOR(i, 1, n) vis[i] = 0, child[i] = 1;
            dfs(u, u);
            int cnt = 0;
            FOR(v, 1, n) {
                if (v == u) continue;
                cnt += (a[u][v] > 0);
            }
            ans += cnt * (cnt - 1);
            FORALL(v, adj[u]) ans -= child[v] * (child[v] - 1);
        }
        cout << ans << '\n';
    }
}

namespace subtask5 {

    const int inf = 1e9;

    int t_time = 0;
    vector<int> num, low, child, depth, vtx, sz;
    vector<vector<int>> p;

    void dfs(int _p, int u) {

        vtx.push_back(u);
        num[u] = ++t_time;
        low[u] = inf;
        FORALL(v, adj[u]) {
            if (v == _p) continue;
            if (num[v]) low[u] = min(low[u], num[v]);
            else {
                depth[v] = depth[u] + 1;
                p[0][v] = u;
                dfs(u, v);
                low[u] = min(low[u], low[v]);
                child[u] += child[v];
            }
        }
    }

    int jump(int u, int l) {

        FORB1(mask, l) u = p[__builtin_ctz(mask)][u];
        return u;
    }

    void main() {

        num.resize(n + 1);
        low.resize(n + 1);
        child.assign(n + 1, 1);
        sz.resize(n + 1);
        depth.resize(n + 1);
        p.assign(20, vector<int>(n + 1));
        long long ans = 0;
        FOR(u, 1, n) {
            if (num[u]) continue;
            vtx.clear();
            dfs(u, u);
            int cnt = _size(vtx);
            ans += 1LL * cnt * (cnt - 1) * (cnt - 2);
            FORALL(v, vtx) sz[v] = cnt;
        }
        FOR(j, 1, 19) FOR(i, 1, n) p[j][i] = p[j - 1][p[j - 1][i]];
        vector<int> f(n + 1);
        FOR(u, 1, n) {
            if (!p[0][u]) continue;
            if (low[u] < num[p[0][u]]) f[p[0][u]] += child[u];
        }
        FOR(u, 1, n) {
            FORALL(v, adj[u]) {
                if (depth[u] > depth[v]) {
                    int value = sz[u] - child[u] + f[u];
                    ans -= 1LL * value * (value - 1);
                }
                else {
                    int r = jump(v, depth[u] - depth[v] - 1);
                    int value = child[r];
                    if (low[r] < num[u]) value += sz[u] - child[u];
                    ans -= 1LL * value * (value - 1);
                }
            }
        }
        cout << ans << '\n';
    }
}

int main() {
    fastio;

    cin >> n >> m;
    adj.resize(n + 1);
    REP(i, m) {
        int u, v;
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    FOR(u, 1, n) {
        sort(adj[u].begin(), adj[u].end());
        adj[u].resize(unique(adj[u].begin(), adj[u].end()) - adj[u].begin());
    }
    if (n <= 10 && m <= 100) subtask1::main();
    else if (n <= 50 && m <= 100) subtask2::main();
    else if (checkSub3()) subtask3::main();
    else if (checkSub45()) {
        if (n <= 1000) subtask4::main();
        else subtask5::main();
    }
    return 0;
}

Compilation message (stderr)

count_triplets.cpp: In function 'void subtask1::main()':
count_triplets.cpp:41:35: warning: suggest parentheses around '-' inside '>>' [-Wparentheses]
   41 |                         if (BIT(v - 1, mask)) continue;
      |                                 ~~^~~
count_triplets.cpp:7:26: note: in definition of macro 'BIT'
    7 | #define BIT(i, x) ((x >> i) & 1)
      |                          ^

• Subtask 1: 5 / 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