Submission #1082765

#	Time	Username	Problem	Language	Result	Execution time	Memory
1082765		Evirir	Capital City (JOI20_capital_city)	C++17	41 / 100	3077 ms	36440 KiB

capital_city

#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
//using namespace __gnu_pbds;

// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx2")
#define setp(x) cout<<fixed<<setprecision(x)
#define sz(x) (int)(x).size()
#define all(x) begin(x), end(x)
#define forn(i,a,b) for(int i=(a);i<(b);i++)
#define fore(i,a,b) for(int i=(a);i<=(b);i++)
#define pb push_back
#define F first
#define S second
#define fbo find_by_order
#define ook order_of_key
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> ii;
typedef vector<ll> vi;
typedef vector<ii> vii;
//template<typename T>
//using pbds = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
void SD(int t=0){ cout<<"PASSED "<<t<<endl; }
template<typename T> void amax(T &a, T b){ a=max(a,b); }
template<typename T> void amin(T &a, T b){ a=min(a,b); }
struct Hash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }
    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};

const ll INF = ll(1e18);
const int MOD = 998244353;
const bool DEBUG = 0;
const int MAXN = 100005;
const int LG = 21;

int n,K;
vector<vector<int>> adj;
vector<int> c, sub, cnt;
vector<bool> cvst;

void dfs_sz(int u, int p)
{
    sub[u] = 1;
    for (const auto v : adj[u])
    {
        if (v == p || cvst[v]) continue;
        dfs_sz(v, u);
        sub[u] += sub[v];
    }
}

int centroid(int u, int tot)
{
    int p = -1;
    while (true)
    {
        bool ok = 1;
        for (const auto v : adj[u])
        {
            if (v == p || cvst[v]) continue;
            if (sub[v] * 2 > tot)
            {
                p = u;
                u = v;
                ok = 0;
                break;
            }
        }
        if (ok) return u;
    }
}

vector<int> s;
vector<int> scnt;
vector<bool> need;
vector<int> needv;
vector<vector<int>> prt;

void dfs(int u, int p)
{
    s.pb(c[u]);
    scnt[c[u]]++;
    if (p != -1) prt[c[u]].pb(c[p]);
    for (const auto v : adj[u])
    {
        if (v == p || cvst[u]) continue;
        dfs(v, u);
    }
}

int ans = 1e9;

void solve(int u)
{
    dfs_sz(u, -1);
    int tot = sub[u];
    u = centroid(u, tot);

    dfs(u, -1);
    vector<int> q{c[u]};
    needv.pb(c[u]);
    need[c[u]] = 1;
    while (!q.empty())
    {
        int curc = q.back(); q.pop_back();
        for (const auto x : prt[curc])
        {
            if (need[x]) continue;
            need[x] = 1;
            needv.pb(x);
            q.pb(x);
        }
    }
    bool ok = 1;
    for (const auto x : needv)
    {
        if (cnt[x] != scnt[x])
        {
            ok = 0;
            break;
        }
    }
    if (ok) amin(ans, sz(needv) - 1);

    // clean up
    for (const auto x : s)
    {
        scnt[x] = 0;
        prt[x].clear();
        need[x] = 0;
    }
    s.clear();
    needv.clear();

    cvst[u] = 1;
    for (const auto v : adj[u])
    {
        if (cvst[v]) continue;
        solve(v);
    }
}

void init()
{
    adj.resize(n);
    c.resize(n);
    cvst.resize(n);
    sub.resize(n);
    cnt.resize(K);
    scnt.resize(K);
    prt.resize(K);
    need.resize(K);
}

int main()
{
    cin.tie(0)->sync_with_stdio(0);

    cin>>n>>K;
    init();

    forn(i,0,n-1)
    {
        int u,v; cin>>u>>v; u--; v--;
        adj[u].pb(v);
        adj[v].pb(u);
    }
    forn(i,0,n)
    {
        cin>>c[i];
        c[i]--;
        cnt[c[i]]++;
    }

    solve(0);
    cout << ans << '\n';

    return 0;
}

• Subtask 1: 1 / 1
• Subtask 2: 10 / 10
• Subtask 3: 30 / 30
• Subtask 4: 0 / 59