Submission #537339

#	Time	Username	Problem	Language	Result	Execution time	Memory
537339		wiwiho	Capital City (JOI20_capital_city)	C++14	11 / 100	3055 ms	32256 KiB

capital_city

#include <bits/stdc++.h>

#define mp make_pair
#define F first
#define S second
#define eb emplace_back
#define iter(a) a.begin(), a.end()
#define lsort(a) sort(iter(a))
#define gsort(a) sort(iter(a), greater<>())

using namespace std;

using pii = pair<int, int>;

int n, m;
vector<int> C;
vector<vector<int>> g;
vector<vector<int>> cv;

vector<int> pr;

void dfs(int now, int p){
    pr[now] = p;
    for(int i : g[now]){
        if(i == p) continue;
        dfs(i, now);
    }
}

int solve(int s){
    dfs(s, s);
    vector<bool> ok(n + 1), use(m + 1);
    queue<int> q;
    int clr = C[s]; use[clr] = true;
    for(int i : cv[clr]) q.push(i);
    ok[s] = true;
    while(!q.empty()){
        int v = q.front();
        q.pop();
        while(!ok[v]){
            ok[v] = true;
            if(!use[C[v]]){
                use[C[v]] = true;
                for(int i : cv[C[v]]) q.push(i);
            }
            v = pr[v];
        }
    }
    int ans = 0;
    for(int i = 1; i <= m; i++) ans += use[i];
    return ans;
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    cin >> n >> m;
    C.resize(n + 1);
    g.resize(n + 1);
    pr.resize(n + 1);
    cv.resize(m + 1);

    for(int i = 1; i < n; i++){
        int u, v;
        cin >> u >> v;
        g[u].eb(v);
        g[v].eb(u);
    }
    for(int i = 1; i <= n; i++){
        cin >> C[i];
        cv[C[i]].eb(i);
    }

    int ans = n;
    for(int i = 1; i <= n; i++){
        ans = min(ans, solve(i) - 1);
    }
    cout << ans << "\n";

    return 0;
}

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