Submission #128732

#	Time	Username	Problem	Language	Result	Execution time	Memory
128732		kuroni	Mergers (JOI19_mergers)	C++17	0 / 100	86 ms	18996 KiB

mergers

#include <bits/stdc++.h>
using namespace std;

const int N = 500005, K = 500005;

int n, k, u, v, ans = 0, a[N], sub[N];
int cur = 0, sum[K], cnt[K];
bool f[N];
vector<int> adj[N];

void add(int u, int p, int val, int av = 0)
{
    cur -= (cnt[a[u]] == sum[a[u]] || cnt[a[u]] == 0);
    cnt[a[u]] += val;
    cur += (cnt[a[u]] == sum[a[u]] || cnt[a[u]] == 0);
    for (int &v : adj[u])
        if (v != p && v != av)
            add(v, u, val, av);
}

int DFS_1(int u, int p = 0)
{
    sub[u] = 1;
    for (int &v : adj[u])
        if (v != p)
            sub[u] += DFS_1(v, u);
    return sub[u];
}

bool DFS_2(int u, int p, bool big)
{
    int mc = 0;
    for (int &v : adj[u])
        if (v != p && sub[v] > sub[mc])
            mc = v;
    for (int &v : adj[u])
        if (v != p && v != mc)
        {
            bool ch = DFS_2(v, u, false);
            if (ch && f[u])
                ans--;
            f[u] ^= ch;
        }
    if (mc != 0)
    {
        bool ch = DFS_2(mc, u, true);
        if (ch && f[u])
            ans--;
        f[u] ^= ch;
    }
    add(u, p, 1, mc);
    if (cur == 0 && u != 1)
    {
        if (!f[u])
            ans++;
        f[u] = true;
    }
    if (!big)
        add(u, p, -1);
    return f[u];
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cin >> n >> k;
    for (int i = 1; i < n; i++)
    {
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    for (int i = 1; i <= n; i++)
    {
        cin >> a[i];
        sum[a[i]]++;
    }
    DFS_1(1);
    DFS_2(1, 0, true);
    cout << ans;
}

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