Submission #642091

#	Time	Username	Problem	Language	Result	Execution time	Memory
642091		vovamr	Transport (COCI19_transport)	C++17	0 / 130	774 ms	15676 KiB

Main

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define fi first
#define se second
#define ll long long
#define ld long double
#define sz(x) ((int)(x).size())
#define all(x) 	(x).begin(), (x).end()
#define pb push_back
#define mpp make_pair
#define ve vector
using namespace std;
using namespace __gnu_pbds;
template<class T> using oset = tree<T,null_type,less_equal<T>,rb_tree_tag,tree_order_statistics_node_update>;
const ll inf = 1e18; const int iinf = 1e9;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
template <typename T> inline bool chmin(T& a, T b) { return (a > b ? a = b, 1 : 0); }
template <typename T> inline bool chmax(T& a, T b) { return (a < b ? a = b, 1 : 0); }

const int N = 1e5 + 10;
ve<pii> gr[N];
int sz[N], used[N], a[N];
inline void dfs1(int v, int p) {
	sz[v] = 1;
	for (auto &[to, w] : gr[v]) {
		if (used[to] || to == p) continue;
		dfs1(to, v); sz[v] += sz[to];
	}
}
inline int centroid(int v, int p, int n) {
	for (auto &[to, w] : gr[v]) {
		if (used[to] || to == p || sz[to] <= n / 2) continue;
		return centroid(to, v, n);
	} return v;
}

ll ans = 0;

int PTR = 0;
pll al[N];

inline void dfs(int v, int p, ll cur_sum, ll mn_sum) {

	if (mn_sum >= 0) ++ans;

	al[PTR++] = {cur_sum, mn_sum};
	for (auto &[to, w] : gr[v]) {
		if (to == p || used[to]) continue;

		ll s = cur_sum + a[v] - w;
		dfs(to, v, s, min(mn_sum, s));
	}
}

oset<ll> sums;

inline void dfs2(int v, int p, int pw, ll tot, ll mn_sum) {
	ll mn = min(0ll, a[v] - pw + mn_sum);
	if (mn >= 0) ans += 1 + sz(sums) - sums.order_of_key(-tot);

	for (auto &[to, w] : gr[v]) {
		if (to == p || used[to]) continue;
		dfs2(to, v, w, tot + a[v] - w, mn);
	}

}

inline void cd(int v, int p) {
	used[v] = 1; dfs1(v, p);

	PTR = 0;
	for (auto &[to, w] : gr[v]) {
		if (to == p || used[to]) continue;
		dfs(to, v, a[v] - w, a[v] - w);
	}

	sums.clear();
	for (int i = 0; i < PTR; ++i) {
		auto &[sum, mn_sum] = al[i];
		sums.insert(mn_sum);
	}

	int pos = 0;
	for (auto &[to, w] : gr[v]) {
		if (to == p || used[to]) continue;
		for (int i = pos; i < pos + sz[to]; ++i) {
			auto &[sum, mn_sum] = al[i];
			sums.erase(sums.lower_bound(mn_sum - 1));
		}

		dfs2(to, v, w, a[to] - w, 0);

		for (int i = pos; i < pos + sz[to]; ++i) {
			auto &[sum, mn_sum] = al[i];
			sums.insert(mn_sum);
		}
		pos += sz[to];
	}

	for (auto &[to, w] : gr[v]) {
		if (to == p || used[to]) continue;
		int c = centroid(to, v, sz[to]);
		cd(c, v);
	}
}

inline void solve() {
	int n;
	cin >> n;
	for (int i = 0; i < n; ++i) cin >> a[i];
	for (int i = 1; i < n; ++i) {
		int v, u, w;
		cin >> v >> u >> w, --v, --u;
		gr[v].pb({u, w}), gr[u].pb({v, w});
	}

	dfs1(0, 0);
	int c = centroid(0, 0, n);

	cd(c, c);
	cout << ans;
}

signed main() {
	ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
	int q = 1; // cin >> q;
	while (q--) solve();
	cerr << fixed << setprecision(3) << "Time execution: " << (double)clock() / CLOCKS_PER_SEC << endl;
}

• Subtask 1: 0 / 13
• Subtask 2: 0 / 13
• Subtask 3: 0 / 13
• Subtask 4: 0 / 13
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• Subtask 10: 0 / 13