Submission #223183

#	Time	Username	Problem	Language	Result	Execution time	Memory
223183		_7_7_	Mergers (JOI19_mergers)	C++14	0 / 100	151 ms	10224 KiB

mergers

#include <bits/stdc++.h>                                           
 
//#define int long long
//#pragma GCC optimize("Ofast")
//#pragma comment(linker, "/stack:200000000")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4")
 
 
#define file(s) freopen(s".in","r",stdin); freopen(s".out","w",stdout);
#define forev(i, b, a) for(int i = (b); i >= (a); --i)
#define forn(i, a, b) for(int i = (a); i <= (b); ++i)
#define all(x) x.begin(), x.end()
#define sz(s) (int)s.size()
#define pb push_back
#define ppb pop_back
#define mp make_pair
#define s second
#define f first
 
 
using namespace std;
 
 
typedef pair < long long, long long > pll;    
typedef pair < int, int > pii;
typedef unsigned long long ull;         
typedef vector < pii > vpii;
typedef vector < int > vi;
typedef long double ldb;  
typedef long long ll;  
typedef double db;                             
 
 
const int dx[] = {1, -1, 0, 0}, dy[] = {0, 0, 1, -1}, block = 333;
const pii base = mp(1171, 3307), Mod = mp(1e9 + 7, 1e9 + 9);
const int inf = 1e9, maxn = 4e5 + 148, mod = 1e9 + 7, N = 1e5 + 11;
const db eps = 1e-12, pi = 3.14159265359;
const ll INF = 1e18;


int n, k, v, u, cnt[N], c[N], tmp, cntC[N], ans, root; 
int tin[N], tout[N], timer, sum, cnt1[N];
bool bad[N];
vi g[N];

void dfs1 (int v, int p = 0) {
	cnt[v] = 1;
	tin[v] = ++timer;
	for (auto to : g[v])
		if (to != p) {
			dfs1(to, v); 
			cnt[v] += cnt[to];
		}	
	tout[v] = timer;
}

void add (int x) {
	++cnt1[x];
	if (cnt1[x] == 1)
		sum += cntC[x];
}

void del (int x) {
	--cnt1[x];
	if (!cnt1[x])
		sum -= cntC[x];
}

void dfs (int v, int p = 0, bool keep = 0) {		
    int u = -1;
	for (auto to : g[v])
		if (to != p && (u == -1 || cnt[to] > cnt[u])) 
			u = to;

	for (auto to : g[v])	
		if (to != p && to != u)
			dfs(to, v, 0);
	
	if (u != -1)	
		dfs(u, v, 1);
	
	for (auto to : g[v]) 
		if (to != p && to != u)	
			for (int i = tin[to]; i <= tout[to]; ++i) 
				add(c[i]);

	add(c[v]);
		
	if (v != root && cnt[v] == sum) 
		bad[v] = 1;
	
	if (!keep) 
		for (int i = tin[v]; i <= tout[v]; ++i)
			del(c[i]);					
}

bool dfs2 (int v, int p = 0) {
	bool was = 0;
	for (auto to : g[v])
		if (to != p && dfs2(to, v)) 
			was = 1;
	if (!was && bad[v])
		++ans;
	bad[v] |= was;
}


main () {
	cin >> n >> k;
	if (n == 2) {
		cout << k - 1 << endl;
		return 0;
	}

	for (int i = 1; i < n; ++i) {
		cin >> v >> u;
		g[v].pb(u);
		g[u].pb(v);
	}

	for (int i = 1; i <= n; ++i) {
		cin >> c[i]; 
		++cntC[c[i]];
	}
	root = 1;
	while (sz(g[root]) == 1)
		++root;

	dfs1(root);
	dfs(root);
	dfs2(root);
	cout << (ans + 1) / 2 << endl;	
}

Compilation message (stderr)

mergers.cpp: In function 'bool dfs2(int, int)':
mergers.cpp:105:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
mergers.cpp: At global scope:
mergers.cpp:108:7: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main () {
       ^

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