제출 #899351

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
899351		juliany2	수도 (JOI20_capital_city)	C++17	100 / 100	485 ms	38932 KiB

capital_city

#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define all(x) (x).begin(), (x).end()

const int N = 2e5 + 7;
int n, k;
vector<int> adj[N], col[N];
int c[N], cnt[N], pt[N];
int sz[N];
bool vis[N], rem[N];
int ans;

int dfs_sz(int v, int p = 0) {
    sz[v] = 1;
    for (int u : adj[v]) {
        if (u != p && !rem[u])
            sz[v] += dfs_sz(u, v);
    }

    return sz[v];
}

int get_centroid(int v, int tot, int p = 0) {
    for (int u : adj[v]) {
        if (u != p && !rem[u]) {
            if (sz[u] * 2 > tot)
                return get_centroid(u, tot, v);
        }
    }

    return v;
}

void prep(int v, int p = 0) {
    pt[v] = p;
    cnt[c[v]]++;
    for (int u : adj[v]) {
        if (u != p && !rem[u])
            prep(u, v);
    }
}

void cls(int v, int p = 0) {
    cnt[c[v]] = 0;
    vis[c[v]] = 0;
    for (int u : adj[v]) {
        if (u != p && !rem[u])
            cls(u, v);
    }
}

void solve(int a = 1) {
    int s = get_centroid(a, dfs_sz(a));

    prep(s);

    queue<int> q;
    q.push(c[s]);
    vis[c[s]] = 1;

    bool ok = 1;
    int used = 0;

    while (q.size()) {
        int x = q.front();
        q.pop();

        if (cnt[x] != col[x].size()) {
            ok = 0;
            break;
        }

        used++;

        for (int v : col[x]) {
            v = pt[v];
            if (v > 0 && !vis[c[v]]) {
                vis[c[v]] = 1;
                q.push(c[v]);
            }
        }
    }

    if (ok)
        ans = min(ans, used - 1);

    cls(s);

    rem[s] = 1;

    for (int u : adj[s]) {
        if (!rem[u])
            solve(u);
    }
}

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

    cin >> n >> k;

    for (int i = 1; i < n; i++) {
        int u, v;
        cin >> u >> v;

        adj[u].push_back(v);
        adj[v].push_back(u);
    }

    for (int i = 1; i <= n; i++) {
        cin >> c[i];
        col[c[i]].push_back(i);
    }

    ans = k - 1;

    solve();

    cout << ans << '\n';

    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

capital_city.cpp: In function 'void solve(int)':
capital_city.cpp:69:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   69 |         if (cnt[x] != col[x].size()) {
      |             ~~~~~~~^~~~~~~~~~~~~~~~

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