Submission #106174

#	Time	Username	Problem	Language	Result	Execution time	Memory
106174		mzhao	Mergers (JOI19_mergers)	C++11	100 / 100	1811 ms	177340 KiB

mergers

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

#define MN 500100
#define x first
#define y second

int N, K, S[MN], tot[MN], ans, g[MN];
vector<int> adj[MN], adj2[MN];
bool bad[MN];
map<int, int>* m[MN];

int f(int x) { if (g[x] != x) g[x] = f(g[x]); return g[x]; }
void merge(int a, int b) { if (f(a) != f(b)) g[f(a)] = f(b); }

map<int, int>* dfs(int n, int p) {
	m[n] = new map<int, int>;
	if (tot[S[n]] > 1) (*m[n])[S[n]] = 1;
	for (int i : adj[n]) if (i != p) {
		map<int, int>* cur = dfs(i, n);
		if (cur->size() > m[n]->size()) swap(cur, m[n]);
		for (auto j : *cur) {
			(*m[n])[j.x] += j.y;
			if ((*m[n])[j.x] == tot[j.x]) m[n]->erase(j.x);
		}
	}
	if (p) {
		if (m[n]->size() == 0) bad[n] = 1;
		else merge(n, p);
	}
	return m[n];
}

void dfs2(int n, int p) {
	if (adj2[n].size() == 1) ans++;
	for (int i : adj2[n]) if (i != p) dfs2(i, n);
}

int main() {
	scanf("%d%d", &N, &K);
	for (int i = 1, A, B; i < N; i++) {
		scanf("%d%d", &A, &B);
		adj[A].push_back(B);
		adj[B].push_back(A);
	}
	for (int i = 1; i <= N; i++) {
		scanf("%d", &S[i]);
		tot[S[i]]++;
		g[i] = i;
	}
	dfs(1, 0);
	for (int i = 1; i <= N; i++) for (int j : adj[i]) {
		int a = f(i), b = f(j);
		if (a != b) adj2[a].push_back(b);
	}
	dfs2(f(1), 0);
	printf("%d\n", (ans+1)/2);
}

Compilation message (stderr)

mergers.cpp: In function 'int main()':
mergers.cpp:40:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &N, &K);
  ~~~~~^~~~~~~~~~~~~~~~
mergers.cpp:42:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &A, &B);
   ~~~~~^~~~~~~~~~~~~~~~
mergers.cpp:47:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &S[i]);
   ~~~~~^~~~~~~~~~~~~

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