제출 #694077

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
694077		tamthegod	Mergers (JOI19_mergers)	C++17	70 / 100	1936 ms	262144 KiB

mergers

// Make the best become better
// No room for laziness
#include<bits/stdc++.h>

#define int long long
#define pb push_back
#define fi first
#define se second
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int maxN = 1e6 + 5;
const int mod = 1e9 + 7;
const ll oo = 1e18;
int n, m;
vector<int> adj[maxN];
vector<int> vc[maxN];
int f[maxN][20];
int depth[maxN];
pair<int, int> e[maxN];
int sum[maxN];
int lab[maxN];
int deg[maxN];
void ReadInput()
{
    cin >> n >> m;
    for(int i=1; i<n; i++)
    {
        int u, v;
        cin >> u >> v;
        e[i] = {u, v};
        adj[u].pb(v);
        adj[v].pb(u);
    }
    for(int i=1; i<=n; i++)
    {
        int x;
        cin >> x;
        vc[x].pb(i);
    }
}
int Findset(int u)
{
    return lab[u] < 0 ? u : lab[u] = Findset(lab[u]);
}
void Unite(int u, int v)
{
    int r = Findset(u), s = Findset(v);
    if(r == s) return;
    if(lab[r] > lab[s]) swap(r, s);
    lab[r] += lab[s];
    lab[s] = r;
}
void dfs(int u, int par)
{
    for(int v : adj[u])
    {
        if(v == par) continue;
        f[v][0] = u;
        depth[v] = depth[u] + 1;
        for(int i=1; i<=18; i++)
            f[v][i] = f[f[v][i - 1]][i - 1];
        dfs(v, u);
    }
}
int lca(int u, int v)
{
    if(depth[u] < depth[v]) swap(u, v);
    int k = depth[u] - depth[v];
    for(int i=18; i>=0; i--)
        if((k >> i) & 1)
            u = f[u][i];
    if(u == v) return u;
    for(int i=18; i>=0; i--)
        if(f[u][i] != f[v][i])
        {
            u = f[u][i];
            v = f[v][i];
        }
    return f[u][0];
}
void dfs1(int u, int par)
{
    for(int v : adj[u])
    {
        if(v == par) continue;
        dfs1(v, u);
        sum[u] += sum[v];
    }
    if(sum[u]) Unite(u, par);
}
void Solve()
{
    dfs(1, 0);
    for(int i=1; i<=m; i++)
    {
        if(vc[i].empty()) continue;
        int tmp = vc[i][0];
        for(int v : vc[i])
        {
            sum[v] += -1;
            tmp = lca(tmp, v);
        }
        sum[tmp] += vc[i].size();
       // cout << tmp << " ";
    }
    memset(lab, -1, sizeof lab);
    dfs1(1, 0);
    map<pair<int, int>, int> mp;
    for(int i=1; i<n; i++)
    {
        int u = Findset(e[i].fi), v = Findset(e[i].se);
        if(u == v || mp[{u, v}]) continue;
        deg[u]++;
        deg[v]++;
        mp[{u, v}] = mp[{v, u}] = 1;
    }
    int cnt = 0;
    for(int i=1; i<=n; i++)
    {
      //  cout << Findset(i) << " ";
        if(lab[i] > 0) continue;
        if(deg[i] == 1) cnt++;
    }
    cout << (cnt + 1) / 2;
}
int32_t main()
{
    //freopen("sol.inp", "r", stdin);
    //freopen("sol.out", "w", stdout);
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    ReadInput();
    Solve();
}

• Subtask 1: 10 / 10
• Subtask 2: 24 / 24
• Subtask 3: 14 / 14
• Subtask 4: 22 / 22
• Subtask 5: 0 / 30