#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));
}
}
ll t[4 * N], p[4 * N];
inline int mg(const ll &a, const ll &b) { return min(a, b); }
inline void mg(const int &v) { t[v] = mg(t[2 * v + 1], t[2 * v + 2]); }
inline void push(int v) {
if (!p[v]) return;
for (int u : {2 * v + 1, 2 * v + 2}) {
t[u] += p[v], p[u] += p[v];
}
p[v] = 0;
}
inline void upd(int v, int vl, int vr, int l, int r, ll x) {
if (l > r) return;
else if (vl == l && vr == r) {
t[v] += x, p[v] += x;
return;
}
push(v);
int m = vl + vr >> 1;
upd(2 * v + 1, vl, m, l, min(r, m), x);
upd(2 * v + 2, m + 1, vr, max(l, m + 1), r, x);
mg(v);
}
inline ll get(int v, int vl, int vr, int l, int r) {
if (l > r) return inf;
else if (vl == l && vr == r) return t[v];
push(v);
int m = vl + vr >> 1;
return min(get(2 * v + 1, vl, m, l, min(r, m)),
get(2 * v + 2, m + 1, vr, max(l, m + 1), r));
}
int n;
oset<ll> sums;
inline void dfs2(int v, int p, int pw, int cnt) {
upd(0, 0, n - 1, 0, cnt - 1, a[v] - pw);
ll mn_sum = get(0, 0, n - 1, 0, cnt);
ll tot = get(0, 0, n - 1, 0, 0);
if (mn_sum >= 0) {
ans += 1 + sz(sums) - sums.order_of_key(-tot);
}
// number of [sum, mn_sum] s.t.
// mn_sum + tot >= 0 => mn_sum >= -tot
for (auto &[to, w] : gr[v]) {
if (to == p || used[to]) continue;
dfs2(to, v, w, cnt + 1);
}
upd(0, 0, n - 1, 0, cnt - 1, pw - a[v]);
}
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, 1);
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() {
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;
}
Compilation message
transport.cpp: In function 'void upd(int, int, int, int, int, long long int)':
transport.cpp:76:13: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
76 | int m = vl + vr >> 1;
| ~~~^~~~
transport.cpp: In function 'long long int get(int, int, int, int, int)':
transport.cpp:85:13: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
85 | int m = vl + vr >> 1;
| ~~~^~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
19 ms |
3156 KB |
Output is correct |
| 2 |
Correct |
19 ms |
3332 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
31 ms |
3580 KB |
Output is correct |
| 2 |
Correct |
44 ms |
3848 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
569 ms |
12560 KB |
Output is correct |
| 2 |
Incorrect |
484 ms |
11672 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
811 ms |
16084 KB |
Output is correct |
| 2 |
Correct |
884 ms |
18248 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Execution timed out |
1085 ms |
21224 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
278 ms |
6868 KB |
Output is correct |
| 2 |
Correct |
162 ms |
6360 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
245 ms |
9812 KB |
Output is correct |
| 2 |
Correct |
448 ms |
9080 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
526 ms |
11924 KB |
Output is correct |
| 2 |
Correct |
568 ms |
12548 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
773 ms |
14668 KB |
Output is correct |
| 2 |
Correct |
744 ms |
15052 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Execution timed out |
1077 ms |
18396 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
