Submission #217973

#	Time	Username	Problem	Language	Result	Execution time	Memory
217973		Vimmer	Duathlon (APIO18_duathlon)	C++14	23 / 100	1124 ms	1048580 KiB

count_triplets

#include <bits/stdc++.h>

#define F first
#define S second
#define sz(x) int(x.size())
#define pb push_back
#define N 100005
#define M ll(998244353)

using namespace std;

typedef long double ld;
typedef long long ll;
typedef short int si;


vector <int> g[N];

bool mk[N], mkr[N];

int i, j, n, m;

ll anser, siz[N], kol;

void calc(int v, int p)
{
    if (p != -1) {siz[p] -= siz[v]; siz[v] += siz[p];}

    for (auto it : g[v]) anser += (siz[v] - 1 - siz[it]) * siz[it];

    for (auto it : g[v]) {if (p == it) continue; calc(it, v);}

    if (p != -1) {siz[v] -= siz[p]; siz[p] += siz[v];}
}

void dfs(int v, int p)
{
    mkr[v] = 1;

    siz[v] = 0;

    for (auto it : g[v])
    {
        if (it == p) continue;

        dfs(it, v);

        siz[v] += siz[it];
    }

    siz[v]++;

    if (i == v) calc(v, -1);
}


bool dostig(int v, int to)
{
    if (mk[v]) return 0;

    if (v == to) return 1;

    mk[v] = 1;

    bool f = 0;

    for (auto it : g[v]) f |= dostig(it, to);

    mk[v] = 0;

    if (f && v != i && !mkr[v]) {mkr[v] = 1; anser++;}

    return f;
}

bool opr(int v, int p)
{
    mkr[v] = 1;

    kol++;

    bool f = 0;

    for (auto it : g[v])
        {
            if (it == p) continue;

            if (mkr[it]) f = 1;
              else f |= opr(it, v);
        }
    return f;
}
int main()
{
    ios_base::sync_with_stdio(0); istream::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    cin >> n >> m;

    for (int i = 0; i < m; i++)
    {
        int x, y;

        cin >> x >> y;

        g[x].pb(y);

        g[y].pb(x);
    }

    if (m <= n - 1)
    {
        for (i = 1; i <= n; i++) if (siz[i] == 0) dfs(i, -1);
    }
    else

    if (n <= 10 && m <= 100)
    {
        for (i = 1; i <= n; i++)
          for (j = 1; j <= n; j++)
            if (i != j){for (int u = 0; u < 51; u++) mkr[u] = 0; dostig(i, j);}
    }
    else
    {
        for (i = 1; i <= n; i++)
        {
            if (mkr[i]) continue;

            kol = 0;

            if (opr(i, -1))
            {
                anser += max(0ll, kol * (kol - 1) * (kol - 2));

                continue;
            }
            else dfs(i, -1);
        }
    }

    cout << anser << endl;
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 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