Submission #943073

#	Time	Username	Problem	Language	Result	Execution time	Memory
943073		12345678	Transport (COCI19_transport)	C++17	0 / 130	533 ms	17832 KiB

Main

#include <bits/stdc++.h>
 
using namespace std;
 
#define ll long long
 
const int nx=1e5+5;
 
ll n, vl[nx], u, v, w, used[nx], sz[nx], ans, t;
vector<pair<ll, ll>> d[nx];
map<ll, int> mp;
 
struct fenwick
{
    ll d[nx];
    void add(int i, int vl)
    {
        while (i<nx) d[i]+=vl, i+=(i&-i);
    }
    ll query(int i)
    {
        ll res=0;
        while (i>0) res+=d[i], i-=(i&-i);
        return res;
    }
} f;
 
int dfssz(int u, int p)
{
    sz[u]=1;
    for (auto [v, w]:d[u]) if (v!=p&&!used[v]) sz[u]+=dfssz(v, u);
    return sz[u]; 
}
 
int findcentroid(int u, int p, int 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(int u, int p, int 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(int u, int p, ll w, ll cost, ll left, bool mode, int 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(int u)
{
    u=findcentroid(u, u, dfssz(u, u));
    used[u]=1;
    mp.clear();
    mp[0]=0;
    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[0], 1);
    for (int i=0; i<d[u].size(); i++) 
    {
        auto [v, w]=d[u][i];
        if (used[v]) continue;
        dfsquery(v, u, u, -w+vl[v], 1);
        dfsadd(v, u, w, 0, 0, 1, 1);
    }
    f.add(mp[0], -1);
    for (auto [v, w]:d[u]) if (!used[v]) dfsadd(v, u, w, 0, 0, 1, -1);
    for (int i=(int)d[u].size()-1; i>=0; i--) 
    {
        auto [v, w]=d[u][i];
        if (used[v]) continue;
        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);
}
 
int main()
{
    cin.tie(NULL)->sync_with_stdio(false);
    cin>>n;
    for (int i=1; i<=n; i++) cin>>vl[i];
    for (int 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;
}

/*
5
5 5 5 5 5
1 2 1
2 3 100
3 4 1
4 5 1

6
1 2 3 3 2 1
1 2 4
2 3 4
3 4 1
4 5 4
5 6 4
*/

Compilation message (stderr)

transport.cpp: In function 'void decomposition(int)':
transport.cpp:71:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   71 |     for (int i=0; i<d[u].size(); i++)
      |                   ~^~~~~~~~~~~~

• Subtask 1: 0 / 13
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• Subtask 3: 0 / 13
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