Submission #943297

#	Time	Username	Problem	Language	Result	Execution time	Memory
943297		12345678	Transport (COCI19_transport)	C++17	130 / 130	521 ms	21444 KiB

Main

#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, dp[nx], t, lft[nx];
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, ll pre, bool mode)
{
    if (sm>=0&&pre>=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, sm+vl[v]-w, min(0ll, pre+(vl[v]-w)), mode);
}
 
void dfsadd(ll u, ll p, bool mode, ll add)
{
    //if (mode&&add==1) cout<<"here "<<u<<' '<<dp[u]<<'\n';
    if (mode) f.add(mp[dp[u]], add);
    else mp[dp[u]]=0;
    for (auto [v, w]:d[u]) 
    {
        if (v!=p&&!used[v]) 
        {
            if (w>lft[u]) dp[v]=dp[u]+(w-lft[u]), lft[v]=0;
            else dp[v]=dp[u], lft[v]=lft[u]-w;
            lft[v]+=vl[v];
            dfsadd(v, u, mode, add);
        }
    }
}
 
void decomposition(ll u)
{
    u=findcentroid(u, u, dfssz(u, u));
    used[u]=1;
    dp[u]=lft[u]=0;
    mp.clear();
    mp[vl[u]]=0;
    t=0;
    //cout<<"root "<<u<<'\n';
    for (auto [v, w]:d[u]) if (!used[v]) dp[v]=w, lft[v]=vl[v], dfsadd(v, u, 0, 0), dfsquery(v, u, u, -w+vl[v], 0, 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], 0, 1), dfsadd(v, u, 1, 1);
    f.add(mp[vl[u]], -1);
    for (auto [v, w]:d[u]) if (!used[v]) dfsadd(v, u, 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], 0, 1), dfsadd(v, u, 1, 1);
    ans+=f.query(mp[vl[u]]);
    for (auto [v, w]:d[u]) if (!used[v]) dfsadd(v, u, 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 (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;
}

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

• Subtask 1: 13 / 13
• Subtask 2: 13 / 13
• Subtask 3: 13 / 13
• Subtask 4: 13 / 13
• Subtask 5: 13 / 13
• Subtask 6: 13 / 13
• Subtask 7: 13 / 13
• Subtask 8: 13 / 13
• Subtask 9: 13 / 13
• Subtask 10: 13 / 13