Submission #733735

#	Time	Username	Problem	Language	Result	Execution time	Memory
733735		GrindMachine	Transport (COCI19_transport)	C++17	91 / 130	267 ms	65536 KiB

Main

// Om Namah Shivaya

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x, y) ((x + y - 1) / (y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i, n) for(int i = 0; i < n; ++i)
#define rep1(i, n) for(int i = 1; i <= n; ++i)
#define rev(i, s, e) for(int i = s; i >= e; --i)
#define trav(i, a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a, b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a, b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif

/*



*/

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

vector<pll> adj[N];
vector<ll> adjc[N];
vector<ll> a(N);
vector<bool> rem(N);
vector<ll> subsiz(N);

ll dfs1(ll u, ll p) {
    subsiz[u] = 1;
    for (auto [v, w] : adj[u]) {
        if (v == p or rem[v]) conts;
        subsiz[u] += dfs1(v, u);
    }
    return subsiz[u];
}

ll dfs2(ll u, ll p, ll nodes) {
    for (auto [v, w] : adj[u]) {
        if (v == p or rem[v]) conts;
        if (subsiz[v] > nodes / 2) {
            return dfs2(v, u, nodes);
        }
    }

    return u;
}

vector<ll> sumup(N), mnprefup(N);
vector<array<ll, 3>> here[N];
ll curr_centroid;
vector<ll> sub_roots;

void dfs3(ll u, ll p, ll uu, ll sumdown, ll mnprefdown) {
    here[curr_centroid].pb({sumup[u], mnprefup[u], mnprefdown});
    if (uu != -1) {
        here[uu].pb({sumup[u], mnprefup[u], mnprefdown});
    }

    // vector<ll> vals = {sumup[u], mnprefup[u], mnprefdown};
    // debug(curr_centroid);
    // debug(u);
    // debug(vals);
    // cout << endl;

    for (auto [v, w] : adj[u]) {
        if (v == p or rem[v]) conts;
        sumup[v] = a[v] - w + sumup[u];
        mnprefup[v] = min(a[v] - w, a[v] - w + mnprefup[u]);
        ll uu2 = uu;
        if (uu == -1) {
            uu2 = v;
            sub_roots.pb(v);
        }
        dfs3(v, u, uu2, sumdown + a[u] - w, min(mnprefdown, sumdown + a[u] - w));
    }
}

ll get(vector<array<ll, 3>> v) {
    vector<ll> vals;
    for (auto [sum, mnprefup, mnprefdown] : v) {
        vals.pb(mnprefdown);
    }

    sort(all(vals));

    ll res = 0;

    for (auto [sum, mnprefup, mnprefdown] : v) {
        if (mnprefup < 0) conts;
        ll cnt = vals.end() - lower_bound(all(vals), -sum);
        if (mnprefdown >= -sum) {
            cnt--;
        }
        res += cnt;
    }

    return res;
}

ll ans = 0;

ll build(ll u, ll p) {
    ll nodes = dfs1(u, -1);
    ll centroid = dfs2(u, -1, nodes);

    if (p != -1) {
        // cout << p << " " << centroid << endl;
        adjc[p].pb(centroid);
    }

    rem[centroid] = 1;
    sumup[centroid] = 0;
    mnprefup[centroid] = 0;
    curr_centroid = centroid;
    sub_roots.clear();

    dfs3(centroid, -1, -1, 0, 0);

    trav(v, sub_roots) {
        ans -= get(here[v]);
        here[v].clear();
    }

    ans += get(here[centroid]);
    here[centroid].clear();

    for (auto [v, w] : adj[centroid]) {
        if (rem[v]) conts;
        build(v, centroid);
    }

    return centroid;
}

// void dfs4(ll u, ll p) {
//     vector<array<ll, 3>> big;
//     big.pb(here[u].back());
//     here[u].pop_back();

//     nodes[u].pb(u);

//     trav(v, adjc[u]) {
//         if (v == p) conts;
//         dfs4(v, u);
//         vector<array<ll, 3>> curr_centroid;
//         trav(node, nodes[v]) {
//             curr_centroid.pb(here[node].back());
//             big.pb(here[node].back());
//             nodes[u].pb(node);
//             here[node].pop_back();
//         }

//         nodes[v].clear();
//         nodes[v].shrink_to_fit();

//         ans -= get(curr_centroid);
//     }

//     // debug(u);
//     // trav(ar, big) {
//     //     vector<ll> v(all(ar));
//     //     debug(v);
//     // }
//     // debug(get(big));
//     // cout << endl;

//     ll temp = get(big);
//     ans += temp;

//     // debug(temp);

//     // if (u == 4) {
//     //     trav(ar, big) {
//     //         vector<ll> v(all(ar));
//     //         debug(v);
//     //     }

//     //     debug(temp);
//     // }

//     // ans += get(big);
// }

void solve(int test_case)
{
    ll n; cin >> n;
    rep1(i, n) cin >> a[i];
    rep1(i, n - 1) {
        ll u, v, w; cin >> u >> v >> w;
        adj[u].pb({v, w}), adj[v].pb({u, w});
    }

    ll root = build(1, -1);
    // dfs4(root, -1);

    cout << ans << endl;
}

int main()
{
    fastio;

    int t = 1;
    // cin >> t;

    rep1(i, t) {
        solve(i);
    }

    return 0;
}

Compilation message (stderr)

transport.cpp: In function 'void solve(int)':
transport.cpp:233:8: warning: unused variable 'root' [-Wunused-variable]
  233 |     ll root = build(1, -1);
      |        ^~~~

• Subtask 1: 13 / 13
• Subtask 2: 13 / 13
• Subtask 3: 13 / 13
• Subtask 4: 0 / 13
• Subtask 5: 0 / 13
• Subtask 6: 13 / 13
• Subtask 7: 13 / 13
• Subtask 8: 13 / 13
• Subtask 9: 13 / 13
• Subtask 10: 0 / 13