#include <bits/stdc++.h>
using namespace std;
#define ll long long
const ll nx=1e5+5;
ll n, vl[nx], u, v, w, used[nx], sz[nx], ans=0, t;
vector<pair<ll, ll>> d[nx];
map<ll, ll> mp;
struct fenwick
{
ll d[nx];
void add(ll i, ll x)
{
while (i<nx) d[i]+=x, i+=(i&-i);
}
ll query(ll i)
{
ll res=0;
while (i>0) res+=d[i], i-=(i&-i);
return res;
}
} f;
ll dfssz(ll u, ll p)
{
sz[u]=1;
for (auto [v, w]:d[u]) if (v!=p&&!used[v]) sz[u]+=dfssz(v, u);
return sz[u];
}
ll findcentroid(ll u, ll p, ll rtsz)
{
for (auto [v, w]:d[u]) if (v!=p&&!used[v]&&2*sz[v]>rtsz) return findcentroid(v, u, rtsz);
return u;
}
void dfsquery(ll u, ll p, ll rt, ll sm, bool mode)
{
if (sm>=0)
{
if (mode) ans+=f.query(mp[sm+vl[rt]]);
else mp[sm+vl[rt]]=0;
}
for (auto [v, w]:d[u]) if (v!=p&&!used[v]) dfsquery(v, u, rt, min(0ll, sm)+vl[v]-w, mode);
}
void dfsadd(ll u, ll p, ll w, ll cost, ll left, bool mode, ll add)
{
if (w>left) cost+=(w-left), left=0;
else left-=w;
if (mode) f.add(mp[cost], add);
else mp[cost]=0;
for (auto [v, w]:d[u]) if (v!=p&&!used[v]) dfsadd(v, u, w, cost, vl[u]+left, mode, add);
}
void decomposition(ll u)
{
u=findcentroid(u, u, dfssz(u, u));
used[u]=1;
mp.clear();
mp[vl[u]]=0;
t=0;
for (auto [v, w]:d[u]) if (!used[v]) dfsadd(v, u, w, 0, 0, 0, 0), dfsquery(v, u, u, -w+vl[v], 0);
for (auto &[x, y]:mp) y=++t;
f.add(mp[vl[u]], 1);
for (auto [v, w]:d[u]) if (!used[v]) dfsquery(v, u, u, -w+vl[v], 1), dfsadd(v, u, w, 0, 0, 1, 1);
f.add(mp[vl[u]], -1);
for (auto [v, w]:d[u]) if (!used[v]) dfsadd(v, u, w, 0, 0, 1, -1);
reverse(d[u].begin(), d[u].end());
for (auto [v, w]:d[u]) if (!used[v]) dfsquery(v, u, u, -w+vl[v], 1), dfsadd(v, u, w, 0, 0, 1, 1);
ans+=f.query(mp[vl[u]]);
for (auto [v, w]:d[u]) if (!used[v]) dfsadd(v, u, w, 0, 0, 1, -1);
for (auto [v, w]:d[u]) if (!used[v]) decomposition(v);
///cout<<u<<' '<<ans<<'\n';
}
int main()
{
cin.tie(NULL)->sync_with_stdio(false);
cin>>n;
for (ll i=1; i<=n; i++) cin>>vl[i];
for (ll i=1; i<n; i++) cin>>u>>v>>w, d[u].push_back({v, w}), d[v].push_back({u, w});
decomposition(1);
cout<<ans;
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
11 ms |
4696 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
17 ms |
4956 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
193 ms |
10584 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
226 ms |
12368 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
389 ms |
15708 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
164 ms |
7140 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
125 ms |
9044 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
328 ms |
9772 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
387 ms |
11272 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
594 ms |
12536 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |