#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector<int>;
using vl = vector<ll>;
#define pb push_back
#define rsz resize
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
using pi = pair<int,int>;
#define f first
#define s second
#define mp make_pair
const int MX = 200005;
const int MOD = (int) (1e9 + 7);
const ll INF = (ll) 1e18;
namespace output {
void pr(int x) { cout << x; }
void pr(long x) { cout << x; }
void pr(ll x) { cout << x; }
void pr(unsigned x) { cout << x; }
void pr(unsigned long x) { cout << x; }
void pr(unsigned long long x) { cout << x; }
void pr(float x) { cout << x; }
void pr(double x) { cout << x; }
void pr(long double x) { cout << x; }
void pr(char x) { cout << x; }
void pr(const char* x) { cout << x; }
void pr(const string& x) { cout << x; }
void pr(bool x) { pr(x ? "true" : "false"); }
template<class T1, class T2> void pr(const pair<T1,T2>& x);
template<class T> void pr(const T& x);
template<class T, class... Ts> void pr(const T& t, const Ts&... ts) {
pr(t); pr(ts...);
}
template<class T1, class T2> void pr(const pair<T1,T2>& x) {
pr("{",x.f,", ",x.s,"}");
}
template<class T> void pr(const T& x) {
pr("{"); // const iterator needed for vector<bool>
bool fst = 1; for (const auto& a: x) pr(!fst?", ":"",a), fst = 0;
pr("}");
}
void ps() { pr("\n"); } // print w/ spaces
template<class T, class... Ts> void ps(const T& t, const Ts&... ts) {
pr(t); if (sizeof...(ts)) pr(" "); ps(ts...);
}
void pc() { cout << "]" << endl; } // debug w/ commas
template<class T, class... Ts> void pc(const T& t, const Ts&... ts) {
pr(t); if (sizeof...(ts)) pr(", "); pc(ts...);
}
#define dbg(x...) pr("[",#x,"] = ["), pc(x);
}
#ifdef LOCAL
using namespace output;
#endif
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template <class T> using Tree = tree<T, null_type, less<T>,
rb_tree_tag, tree_order_statistics_node_update>;
int n;
ll a[MX];
bool blocked[MX];
vector<pair<ll, int>> adj[MX];
ll ans = 0;
Tree<pair<ll, int>> vals[MX];
ll dist[MX];
ll mdist[MX];
int sz[MX];
void dfs(int v, int p) {
if (p != -1 && mdist[v] >= 0) ++ans;
dist[v] += a[v];
for (pi to : adj[v]) {
if (blocked[to.f]) continue;
if (to.f != p) {
dist[to.f] = dist[v] - to.s;
mdist[to.f] = min(mdist[v], dist[to.f]);
dfs(to.f, v);
}
}
}
void comb(Tree<pair<ll, int>> &a, Tree<pair<ll, int>> &b) {
if (sz(a) < sz(b)) swap(a, b);
for (auto x : b) {
a.insert(x);
}
}
void dfs2(int v, int p) {
if (p != -1) vals[v].insert(mp(dist[v], v));
for (pi to : adj[v]) {
if (blocked[to.f]) continue;
if (to.f != p) {
dfs2(to.f, v);
comb(vals[v], vals[to.f]);
}
}
// dbg(v, vals[v]);
int rem = vals[v].order_of_key(mp(dist[v], INT_MIN));
for (int i = 0; i < rem; i++) {
vals[v].erase(vals[v].begin());
}
// dbg(v, vals[v]);
}
vi order;
void dfs3(int v, int p) {
for (pi to : adj[v]) {
if (blocked[to.f]) continue;
if (to.f != p) {
dfs3(to.f, v);
}
}
order.pb(v);
}
void solve(int root) {
for (int i = 0; i < n; i++) dist[i] = 0;
for (int i = 0; i < n; i++) mdist[i] = INF;
mdist[0] = 0;
for (int i = 0; i < n; i++) vals[i].clear();
dfs(root, -1);
dfs2(root, -1);
Tree<pair<ll, int>> &fin = vals[root];
// dbg(fin);
ans += sz(fin);
for (pi to : adj[root]) {
if (blocked[to.f]) continue;
dfs3(to.f, root);
vector<pi> todo;
for (int x : order) {
int ind = fin.order_of_key(mp(dist[x], x));
pair<ll, int> cval = *fin.find_by_order(ind);
if (cval.f == dist[x] && cval.s == x) {
fin.erase(mp(dist[x], x));
// dbg("REMOVING", dist[x], x);
todo.pb(mp(dist[x], x));
}
}
// dbg(to.f, fin);
for (int x : order) {
ll cdist = mdist[x];
// dbg(x, cdist);
// dbg(x, -cdist + a[root]);
// dbg(ans);
ans += sz(fin) - fin.order_of_key(mp(-cdist + a[root], INT_MIN));
// dbg(ans);
}
for (pair<ll, int> x : todo) {
// dbg("ADDING BACK: ", x);
fin.insert(x);
}
order.clear();
}
// ps(ans);
}
void dfs4(int v, int p) {
sz[v] = 1;
for (pi to : adj[v]) {
if (blocked[to.f]) continue;
if (to.f != p) {
dfs4(to.f, v);
sz[v] += sz[to.f];
}
}
}
int find(int v, int p) {
bool found = false;
for (pi to : adj[v]) {
if (blocked[to.f]) continue;
if (to.f != p) {
if (sz[to.f] > n / 2) {
found = true;
return find(to.f, v);
}
}
}
if (!found) {
return v;
}
}
void go(int root) {
dfs4(root, -1);
int cc = find(root, -1);
solve(cc);
// dbg(cc, ans);
blocked[cc] = true;
for (pi to : adj[cc]) {
if (!blocked[to.f]) {
go(to.f);
}
}
}
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
cin >> n;
for (int i = 0; i < n; i++) cin >> a[i];
for (int i = 0; i < n - 1; i++) {
int u, v, w; cin >> u >> v >> w;
u--, v--;
adj[u].pb(mp(v, w)), adj[v].pb(mp(u, w));
}
// solve(1);
go(0);
ps(ans);
}
Compilation message
transport.cpp: In function 'int main()':
transport.cpp:227:5: error: 'ps' was not declared in this scope; did you mean 'output::ps'?
227 | ps(ans);
| ^~
| output::ps
transport.cpp:53:41: note: 'output::ps' declared here
53 | template<class T, class... Ts> void ps(const T& t, const Ts&... ts) {
| ^~
transport.cpp: In function 'int find(int, int)':
transport.cpp:200:1: warning: control reaches end of non-void function [-Wreturn-type]
200 | }
| ^
