Submission #1180045

#	Time	Username	Problem	Language	Result	Execution time	Memory
1180045		Hamed_Ghaffari	Mergers (JOI19_mergers)	C++20	100 / 100	233 ms	57524 KiB

mergers

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

const int MXN = 5e5+2;

int n, k, dsu[MXN], h[MXN], deg[MXN], sta[MXN], par[MXN];
vector<int> g[MXN];

void dfs(int v, int p=-1) {
    for(int u : g[v])
        if(u!=p)
            par[u] = v,
            h[u] = h[v]+1,
            dfs(u, v);
}

int find(int v) { return v==dsu[v] ? v : dsu[v]=find(dsu[v]); }

void merge(int u, int v) {
    u = find(u), v = find(v);
    while(u!=v) {
        if(h[u]<h[v]) swap(u, v);
        dsu[u] = par[u];
        u = find(u);
    }
}

int32_t main() {
    cin.tie(0); cout.tie(0); ios_base::sync_with_stdio(0);
    cin >> n >> k;
    for(int i=0,u,v; i<n-1; i++) {
        cin >> u >> v; u--; v--;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    dfs(0);
    fill(sta, sta+k, -1);
    iota(dsu, dsu+n, 0);
    for(int i=0, s; i<n; i++) {
        cin >> s; s--;
        if(sta[s]!=-1) merge(sta[s], i);
        else sta[s] = i;
    }
    for(int i=0, ii, jj; i<n; i++)
        for(int j : g[i])
            if(i<j) {
                ii = find(i), jj = find(j);
                if(ii!=jj) deg[ii]++, deg[jj]++;
            }
    int ans=0;
    for(int i=0; i<n; i++) ans += i==dsu[i] && deg[i]==1;
    cout << ((ans+1)>>1) << '\n';
    return 0;
}

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