Submission #471417

#	Time	Username	Problem	Language	Result	Execution time	Memory
471417		shrimb	Mergers (JOI19_mergers)	C++17	0 / 100	148 ms	32484 KiB

mergers

#include"bits/stdc++.h"
#define int long long
#define endl '\n'
#define USACO(x) ifstream cin ((string)#x + ".in"); ofstream cout((string)#x + ".out")
using namespace std;
int n, k;
vector<int> adj[500001];
int s[500001];
int tot[500001];
int subtree[500001];

map<int,int>* s2b[500001];
int cnt[5000001];
bool bad[5000001];

void inc (int a, int b, int v) {
    (*s2b[a])[b] += v;
    if ((*s2b[a])[b] == tot[b]) cnt[a]++;
}

int ans = INT_MAX;

void dfs (int cur, int par) {
    // cerr << cur << " " << par << endl;
    subtree[cur] = 1;
    if (adj[cur].size() == 1 and cur != 1) {
        s2b[cur] = new map<int,int>();
        inc(cur, s[cur], 1);
        ans = min(ans, (int)abs(cnt[cur] - (int)((*s2b[cur]).size())));
        bad[cur] = (cnt[cur] == (int)((*s2b[cur]).size()));
        return;
    }

    int best = -1;
    for (int i : adj[cur]) {
        if (i != par) {
            dfs(i, cur);
            subtree[cur] += subtree[i];
            if (best == -1 or subtree[i] > subtree[best]) best = i;
        }
    }

    s2b[cur] = s2b[best];
    cnt[cur] = cnt[best];

    for (int i : adj[cur]) {
        if (i != par and i != best) {
            for (auto j : (*s2b[i])) {
                inc(cur, j.first, j.second);
            }
            delete s2b[i];
        }
    }

    inc(cur, s[cur], 1);

    ans = min(ans, (int)abs(cnt[cur] - (int)((*s2b[cur]).size())));
    bad[cur] = (cnt[cur] == (int)((*s2b[cur]).size()));
}

int calc_ans (int cur, int par) {
    int ret = 0;
    for (int i : adj[cur]) {
        if (i != par) {
            ret += calc_ans(i, cur);
        }
    }
    if (ret == 0 and cur != 1) ret += bad[cur];
    return ret;
}


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

    cin >> n >> k;
    for (int i = 1 ; i < n ; i++) {
        int a, b;
        cin >> a >> b;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }

    for (int i = 1 ; i <= n ; i++) {
        cin >> s[i];
        tot[s[i]]++;
    }
    dfs(1, 0);
    cout << ceil(calc_ans(1, 0) / 2.0);


}

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