//C.cpp
#include<bits/stdc++.h>
using namespace std;
//#include<ext/pb_ds/assoc_container.hpp>
//#include<ext/pb_ds/tree_policy.hpp>
//
// #pragma GCC optimize("unroll-loops")
// #pragma GCC optimize("Ofast")
// #pragma GCC optimize("-O3")
// #pragma GCC optimize("no-stack-protector")
// #pragma GCC optimize("fast-math")
//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx")
//#define LOCAL
#define sim template < class c
#define ris return * this
#define dor > debug & operator <<
#define eni(x) sim > typename \
enable_if<sizeof dud<c>(0) x 1, debug&>::type operator<<(c i) {
sim > struct rge { c b, e; };
sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c* x) -> decltype(cerr << *x, 0);
sim > char dud(...);
struct debug {
#ifndef LOCAL
~debug() { cerr << endl; }
eni(!=) cerr << boolalpha << i; ris; }
eni(==) ris << range(begin(i), end(i)); }
sim, class b dor(pair < b, c > d) {
ris << "(" << d.first << ", " << d.second << ")";
}
sim dor(rge<c> d) {
*this << "[";
for (auto it = d.b; it != d.e; ++it)
*this << ", " + 2 * (it == d.b) << *it;
ris << "]";
}
#else
sim dor(const c&) { ris; }
#endif
};
#define imie(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "
#define fi first
#define f first
#define se second
#define s second
#define vi_a vector<int>a;
#define p_b push_back
////////////////////////////////???????????????CHECK THIS OUT???????????????//////////////////////////////
#define ll long long
typedef unsigned long long ull;
////////////////////////////////???????????????CHECK THIS OUT???????????????//////////////////////////////
#define ld long double
#define pll pair<ll,ll>
#define pii pair<int,int>
#define m_p make_pair
#define fast_io cin.tie(0);cout.tie(0);ios_base::sync_with_stdio(0);
#define all(x) x.begin(),x.end()
#define getfiles ifstream cin("input.txt");ofstream cout("output.txt");
#define pw(x) (1ll << x)
#define sz(x) (int)x.size()
#define endl "\n"
#define rall(x) x.rbegin(),x.rend()
#define len(a) (ll)a.size()
#define rep(x,l,r) for(ll x=l;x<r;x++)
//using namespace __gnu_pbds;
ld eps = (ld)1 / 1e6;
const ld pi=3.14159265359;
ll inf = 2e9,mod1=1e9+7;
ll sqr(ll a) { return a * a; }
ll qb(ll a) { return a * a * a; }
template<typename T> bool umax(T& a, T b) {return a<b?a=b,1:0;}
template<typename T> bool umin(T& a, T b) {return b<a?a=b,1:0;}
bool is_prime(ll val){for(ll i=2;i<=sqrt(val);i++)if(val%i==0)return 0; return 1;}
ll gcd(ll a, ll b) { return !a ? b : gcd(b % a, a); }
ll binpow(ll a, ll b, ll mod) { return b ? (b % 2 ? (a * (sqr(binpow(a, b / 2, mod)) % mod)) % mod : sqr(binpow(a, b / 2, mod)) % mod) : 1; }ll binmult(ll a, ll b, ll mod) { return b ? (b % 2 ? (2 * binmult(a, b / 2, mod) + a) % mod : (2 * binmult(a, b / 2, mod)) % mod) : 0; }
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
const ll R=1e4;
const ll tx[4]={0,0,-1,1};
const ll ty[4]={-1,1,0,0};
const char rev_to[4]={'E','W','N','S'};
const int M=999999937;
const int N=1e5+2;
const int ppp=73;
const int Y=1;
const int X=0;
typedef pair<long long,int> pli;
//typedef tree<pli,null_type,less<pli>,rb_tree_tag,tree_order_statistics_node_update> o_st;
auto rnd=bind(uniform_int_distribution<ll>(1,125),mt19937(time(0)));
void bad(){
cout<<"-1";
exit(0);
}
int sz[N];
bool mrk[N];
vector<pii>g[N];
void dfs1(int v,int p){
sz[v]=1;
for(auto &z : g[v]){
if(mrk[z.f] || z.f==p) continue;
dfs1(z.f,v);
sz[v]+=sz[z.f];
}
}
int get_centr(int v,int p,int s){
for(auto &z : g[v]){
if(mrk[z.f] || z.f==p) continue;
if(sz[z.f]>=s/2) return get_centr(z.f,v,s);
}
return v;
}
vector<pli>f,s;
ll mntoroot[N],mnfromroot[N],smfromroot[N],smtoroot[N];
int pr[N],cnt[N],a[N];
ll a1=0;
void dfs2(int v,int p,int x){
for(auto &z : g[v]){
if(mrk[z.f] || z.f==p) continue;
smfromroot[z.f]=smfromroot[v]-z.s+a[v];
smtoroot[z.f]=smtoroot[v]-z.s+a[z.f];
mntoroot[z.f]=min((ll)a[z.f]-z.s,mntoroot[v]+a[z.f]-z.s);
mnfromroot[z.f]=min(mnfromroot[v],smfromroot[z.f]);
x=(v==p ? z.f : x);
if(mntoroot[z.f]>=0) a1++,f.p_b({smtoroot[z.f],x});
a1+=(mnfromroot[z.f]>=0);
s.p_b({-mnfromroot[z.f],x});
pr[z.f]=x;
// debug()<<imie(z.f)<<imie(a1);
dfs2(z.f,v,x);
}
}
void cd(int v){
dfs1(v,v);
f.clear();
s.clear();
v=get_centr(v,v,sz[v]);
mntoroot[v]=0;mnfromroot[v]=0;smtoroot[v]=0;smfromroot[v]=0;
dfs2(v,v,v);
sort(all(f));sort(all(s));
int j=0;
// debug()<<imie(f)<<imie(s);
for(int i=0;i<sz(f);i++){
while(j<sz(s) && f[i].f>=s[j].f){
cnt[s[j].s]++;
j++;
}
a1+=j-cnt[f[i].s];
// debug()<<imie(a1);
}
for(auto &z : s){
cnt[z.s]=0;
}
mrk[v]=1;
for(auto &z : g[v]){
if(mrk[z.f]) continue;
cd(z.f);
}
}
int n,v,u,w;
signed main()
{
fast_io;
cin>>n;
for(int i=0;i<n;i++) cin>>a[i];
for(int i=1;i<n;i++){
cin>>v>>u>>w;--v;--u;
g[v].p_b({u,w});
g[u].p_b({v,w});
}
cd(0);
cout<<a1;
return 0;
}
/*
4 3
*/
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
7 ms |
3200 KB |
Output is correct |
| 2 |
Correct |
7 ms |
3328 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
8 ms |
3456 KB |
Output is correct |
| 2 |
Correct |
9 ms |
3712 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
81 ms |
10732 KB |
Output is correct |
| 2 |
Correct |
66 ms |
9468 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
103 ms |
13236 KB |
Output is correct |
| 2 |
Correct |
110 ms |
14704 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
146 ms |
17256 KB |
Output is correct |
| 2 |
Correct |
173 ms |
19556 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
59 ms |
6560 KB |
Output is correct |
| 2 |
Correct |
34 ms |
6008 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
66 ms |
9452 KB |
Output is correct |
| 2 |
Correct |
88 ms |
8304 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
138 ms |
11204 KB |
Output is correct |
| 2 |
Correct |
142 ms |
11116 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
212 ms |
13548 KB |
Output is correct |
| 2 |
Correct |
203 ms |
13616 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
265 ms |
16424 KB |
Output is correct |
| 2 |
Correct |
242 ms |
14568 KB |
Output is correct |
