Submission #1247427

#	Time	Username	Problem	Language	Result	Execution time	Memory
1247427		tvgk	우호 조약 체결 (JOI14_friends)	C++20	100 / 100	43 ms	15944 KiB

friends

#include<bits/stdc++.h>
using namespace std;
#define task "a"
#define se second
#define fi first
#define ll long long
#define ii pair<ll, ll>
const long mxN = 1e5 + 7;

int n, m;
bool vis[mxN];
ll dsu[mxN];
vector<int> w[mxN];

int Find(int j)
{
    if (dsu[j] < 0)
        return j;
    else
        return dsu[j] = Find(dsu[j]);
}

void Union(int u, int v)
{
    u = Find(u);
    v = Find(v);

    if (u == v)
        return;

    dsu[v] += dsu[u];
    dsu[u] = v;
}

void DFS(int j, int mut)
{
    Union(j, mut);

    if (vis[j])
        return;
    vis[j] = 1;

    for (int i : w[j])
        DFS(i, mut);
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    //freopen(task".INP", "r", stdin);
    //freopen(task".OUT", "w", stdout);

    cin >> n >> m;
    for (int i = 1; i <= m; i++)
    {
        int u, v;
        cin >> u >> v;
        w[u].push_back(v);
    }

    for (int i = 1; i <= n; i++)
        dsu[i] = -1;

    for (int i = 1; i <= n; i++)
    {
        if (w[i].size() <= 1)
            continue;

        for (int j : w[i])
            DFS(j, w[i][0]);
    }

    ll ans = 0;
    for (int i = 1; i <= n; i++)
    {
        if (dsu[i] < 0)
            ans += dsu[i] * (dsu[i] + 1);
        for (int j : w[i])
        {
            if (Find(j) != Find(i))
                ans++;
        }
    }
    cout << ans;
}

• Subtask 1: 5 / 5
• Subtask 2: 30 / 30
• Subtask 3: 65 / 65