제출 #471865

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
471865		shrimb	Mergers (JOI19_mergers)	C++17	0 / 100	209 ms	107776 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;
const int maxN = 1000001;
int ROOT;
int n, k;
vector<int> adj[maxN];
int s[maxN];
int tot[maxN];
int subtree[maxN];

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

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

int cunt = 0;

void subtrees (int cur, int par) {
    subtree[cur] = 1;
    for (int i : adj[cur]) {
        if (i != par) {
            subtrees(i, cur);
            subtree[cur] += subtree[i];
        }
    }
}

void dfs (int cur, int par) {
    if (adj[cur].size() == 1 and cur != ROOT) {
        inc(cur, s[cur], 1);
        bad[cur] = (cnt[cur] == (int)((*s2b[cur]).size()));
        return;
    }
    int best = -1;
    for (int i : adj[cur]) {
        if (i != par) {
            dfs(i, cur);
            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);
            }
            (*s2b[i]).clear();
        }
    }

    inc(cur, s[cur], 1);
    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) {
            int x = calc_ans(i, cur);
            if (bad[cur] == 0 or cur == ROOT) {
                cunt += min(ret, x);
                // cerr << cunt << endl;
                ret = abs(ret - x);
            }
            else ret += x;
        }
    }
    if (ret == 0 and cur != ROOT) ret += bad[cur];
    return ret;
}


signed main() {
    for (auto& i : s2b) i = new map<int,int>();
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    cin >> n >> k;
    ROOT = rand() % n + 1;
    if (n ==1) {
        cout << 0 << endl;
        return 0;
    }
    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]]++;
    }

    subtrees(1, 0);

    int cur = 1;
    bool good = 1;
    vector<bool> vis(maxN);
    do {
        vis[cur] = 1;
        good = 0;
        int v = 0;
        for (int i : adj[cur]) if (!vis[i] and subtree[i] > (n / 2)) {v = i;good = 1;}
        if (good) cur = v;
    } while (good);
    ROOT = cur;
    dfs(ROOT, 0);
    // for (int i = 1 ; i <= n ; i++) cout << bad[i] << " "; cout << endl;
    int x = calc_ans(ROOT, 0);
    cout << cunt + (x ? 1 + ceil((x-1)/2.0) : 0);


}

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