Submission #107228

#	Time	Username	Problem	Language	Result	Execution time	Memory
107228		eriksuenderhauf	Mergers (JOI19_mergers)	C++11	100 / 100	1522 ms	86620 KiB

mergers

//#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define mem(a,v) memset((a), (v), sizeof (a))
#define enl printf("\n")
#define case(t) printf("Case #%d: ", (t))
#define ni(n) scanf("%d", &(n))
#define nl(n) scanf("%lld", &(n))
#define nai(a, n) for (int i = 0; i < (n); i++) ni(a[i])
#define nal(a, n) for (int i = 0; i < (n); i++) nl(a[i])
#define pri(n) printf("%d\n", (n))
#define prl(n) printf("%lld\n", (n))
#define pii pair<int, int>
#define pil pair<int, long long>
#define pll pair<long long, long long>
#define vii vector<pii>
#define vil vector<pil>
#define vll vector<pll>
#define vi vector<int>
#define vl vector<long long>
#define pb push_back
#define mp make_pair
#define fi first
#define se second
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef cc_hash_table<int,int,hash<int>> ht;
typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> oset;
const double pi = acos(-1);
const int MOD = 1e9 + 7;
const ll INF = 1e16 + 7;
const int MAXN = 1e6 + 5;
const double eps = 1e-9;
int deg[MAXN], col[MAXN], lo[MAXN], disc[MAXN];
int ind[MAXN];
pii edg[MAXN];
vii adj[MAXN];
int t = 0, vis[MAXN], cnt = 0, br[MAXN];

void dfs(int u, int p) {
	disc[u] = lo[u] = t++;
	vis[u] = 1;
	for (pii nx: adj[u]) {
		int v, id; tie(v, id) = nx;
		if (!vis[v]) {
			dfs(v, id);
			lo[u] = min(lo[u], lo[v]);
			if (disc[u] < lo[v])
				br[id] = 1;
		} else if (id != p)
			lo[u] = min(lo[u], disc[v]);
	}
}

int curC = 0;

void bfs(int cur) {
	deque<int> pq;
	pq.pb(cur);
	vis[cur] = 1;
	while (!pq.empty()) {
		int u = pq.front(); pq.pop_front();
		ind[u] = curC;
		for (pii nx: adj[u]) {
			int v, id; tie(v, id) = nx;
			if (!br[id] && !vis[v]) {
				pq.pb(v);
				vis[v] = 1;
			}
		}
	}
	curC++;
}

int main() {
	int n, k;
	scanf("%d %d", &n, &k);
	for (int i = 1; i < n; i++) {
		int u, v;
		scanf("%d %d", &u, &v);
		edg[i] = {--u, --v};
	}
	for (int i = 0; i < n; i++) {
		ni(col[i]); --col[i];
	}
	for (int i = 1; i < n; i++) {
		int u, v; tie(u, v) = edg[i];
		u = col[u], v = col[v];
		if (u == v) continue;
		adj[u].pb({v, cnt});
		adj[v].pb({u, cnt});
		cnt++;
	}
	dfs(0, -1);
	mem(vis,0);
	for (int i = 0; i < k; i++)
		if (!vis[i])
			bfs(i);
	for (int i = 0; i < k; i++) {
		for (pii nx: adj[i]) {
			int u, id; tie(u, id) = nx;
			if (!br[id]) continue;
			deg[ind[u]]++;
		}
	}
	int lvs = 0;
	for (int i = 0; i < curC; i++)
		if (deg[i] == 1)
			lvs++;
	pri((lvs+1)/2);
    return 0;
}

Compilation message (stderr)

mergers.cpp: In function 'int main()':
mergers.cpp:79:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d", &n, &k);
  ~~~~~^~~~~~~~~~~~~~~~~
mergers.cpp:82:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &u, &v);
   ~~~~~^~~~~~~~~~~~~~~~~
mergers.cpp:8:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
 #define ni(n) scanf("%d", &(n))
               ~~~~~^~~~~~~~~~~~
mergers.cpp:86:3: note: in expansion of macro 'ni'
   ni(col[i]); --col[i];
   ^~

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