Submission #602993

#	Time	Username	Problem	Language	Result	Execution time	Memory
602993		benjaminkleyn	Duathlon (APIO18_duathlon)	C++17	0 / 100	119 ms	13012 KiB

count_triplets

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

int n, m;
vector<int> g[100000];
int par[100000];
int sz[100000];

int find(int u)
{
    if (par[u] == u)
        return u;
    return par[u] = find(par[u]);
}

void unite(int u, int v)
{
    u = find(u), v = find(v);
    if (u != v)
        par[v] = u, sz[u] = sz[v] = sz[u] + sz[v];
}

bool vis[100000];
pair<int,int> dfs(int u)
{
    vis[u] = true;
    int size = 0, count = 0;
    for (int v : g[u])
        if (!vis[v])
        {
            auto [sub_size, sub_count] = dfs(v);
            size += sub_size;
            count += sub_count;
        }

    return make_pair(size + 1, count + size * (sz[u] - size - 1));
}

int main()
{
    cin >> n >> m;
    for (int i = 0; i < n; i++)
        par[i] = i, sz[i] = 1;
    for (int i = 0, u, v; i < m; i++)
    {
        cin >> u >> v;
        unite(u-1, v-1);
        g[u-1].push_back(v-1);
        g[v-1].push_back(u-1);
    }

    ll res = 0;
    for (int i = 0; i < n; i++)
        if (par[i] == i)
            res += dfs(i).second;

    cout << res << '\n';

    return 0;
}

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