Submission #106172

#	Time	Username	Problem	Language	Result	Execution time	Memory
106172		mzhao	Mergers (JOI19_mergers)	C++11	0 / 100	60 ms	47584 KiB

mergers

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

#ifdef DEBUG
#define D(x...) printf(x)
#else
#define D(x...)
#endif

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

int N, K, S[MN];
vector<int> adj[MN];

int tot[MN], cnt[MN], ans, dep[MN], par[MN];
int cur[3100][3100];
bool bad[MN];

int g[3100];

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); }

vector<int> adj2[MN];

void dfs(int n, int p, int d) {
	dep[n] = d;
	par[n] = p;
	for (int i = 1; i <= K; i++) cur[n][i] = cnt[i];
	cnt[S[n]]++;
	for (int i : adj[n]) if (i != p) {
		dfs(i, n, d+1);
	}
	for (int i = 1; i <= K; i++) cur[n][i] = cnt[i]-cur[n][i];
	if (n == 1) return;
	bool f = 1;
	for (int i = 1; i <= K; i++) if (cur[n][i] && cur[n][i] != tot[i]) {
		f = 0;
		break;
	}
	bad[n] = f;
	if (!f) merge(n, p);
}

int leaves;

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

int main() {
	scanf("%d%d", &N, &K);
	assert(N <= 3000);
	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, 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);
				adj2[b].push_back(a);
			}
		}
	}
	dfs2(f(1), 0);
	printf("%d\n", (leaves+1)/2);
}

Compilation message (stderr)

mergers.cpp: In function 'int main()':
mergers.cpp:55:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &N, &K);
  ~~~~~^~~~~~~~~~~~~~~~
mergers.cpp:58:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &A, &B);
   ~~~~~^~~~~~~~~~~~~~~~
mergers.cpp:63:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &S[i]);
   ~~~~~^~~~~~~~~~~~~

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