Submission #547639

#	Time	Username	Problem	Language	Result	Execution time	Memory
547639		ngpin04	Zagrade (COI17_zagrade)	C++14	100 / 100	877 ms	43628 KiB

zagrade

#include <bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define TASK ""
#define ALL(x) (x).begin(), (x).end() 
using namespace std;
template <typename T1, typename T2> bool mini(T1 &a, T2 b) {
	if (a > b) {a = b; return true;} return false;
}
template <typename T1, typename T2> bool maxi(T1 &a, T2 b) {
	if (a < b) {a = b; return true;} return false;
}
const int N = 3e5 + 5; 
const int oo = 1e9;
const long long ooo = 1e18;
const int mod = 1e9 + 7; // 998244353;
const long double pi = acos(-1);

vector <int> adj[N];

long long ans;

int cnt[N];
int sz[N];
int a[N];
int n;

bool bk[N];

int dfs(int u, int p = -1) {
	int &res = sz[u];
	res = 1;
	for (int v : adj[u]) 
		if (v != p && !bk[v]) 
			res += dfs(v, u);
	return res;
}

int getcen(int u, int S, int p = -1) {
	for (int v : adj[u]) 
		if (v != p && !bk[v] && sz[v] * 2 >= S) 
			return getcen(v, S, u);
	return u;
}

void dfs(int u, int cur, int minval, int p = -1) {
	cur += a[u];
	mini(minval, cur);

	if (cur == minval && cur <= 0)
		ans += cnt[-cur];

	for (int v : adj[u]) 
		if (v != p && !bk[v]) 
			dfs(v, cur, minval, u);
}

void solve(int u, int cur, int minval, int p = -1) {
	cur += a[u];
	minval += a[u];
	mini(minval, 0);

	if (minval == 0) 
		cnt[cur]++;

	for (int v : adj[u]) 
		if (v != p && !bk[v]) 	
			solve(v, cur, minval, u);
}

void dfs1(int u, int cur = 0, int p = -1) {
	cur += a[u];
	if (cur < 0)
		return;

	if (cur == 0)
		ans++;

	for (int v : adj[u]) 
		if (v != p && !bk[v])
			dfs1(v, cur, u);
}

void centroid(int u) {
	int s = dfs(u);
	int cen = getcen(u, s);
	bk[cen] = true;
	// cerr << "centroid: " << cen << "\n";

	for (int v : adj[cen]) if (!bk[v]) {
		dfs(v, 0, 0, cen);
		solve(v, a[cen], min(a[cen], 0), cen);
	}

	ans += cnt[0];

	for (int i = 0; i <= s; i++)
		cnt[i] = 0;

	reverse(ALL(adj[cen]));

	for (int v : adj[cen]) if (!bk[v]) {
		dfs(v, 0, 0, cen);
		solve(v, a[cen], min(a[cen], 0), cen);
	}

	for (int i = 0; i <= s; i++)
		cnt[i] = 0;

	dfs1(cen);

	// cerr << ans << "\n";

	for (int v : adj[cen]) {
		if (!bk[v]) {
			// cerr << cen << " " << v << "\n";
			centroid(v);
		}
	}
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	#ifdef ONLINE_JUDGE
	// freopen(TASK".inp","r",stdin);
	// freopen(TASK".out","w",stdout);
	#endif
	cin >> n;
	for (int i = 1; i <= n; i++) {
		char c; cin >> c;
		a[i] = (c == '(') ? 1 : -1;
	}

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

	centroid(1);

	cout << ans;
	return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 30 / 30
• Subtask 3: 60 / 60