Submission #733745

#	Time	Username	Problem	Language	Result	Execution time	Memory
733745		GrindMachine	Transport (COCI19_transport)	C++17	130 / 130	263 ms	26528 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> 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});
    }

    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 [sumup, mnprefup, mnprefdown] : v) {
        vals.pb(mnprefdown);
    }

    sort(all(vals));

    ll res = 0;

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

    return res;
}

ll ans = 0;

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

    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();
        here[v].shrink_to_fit();
    }

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

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

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});
    }

    build(1, -1);
    cout << ans << endl;
}

int main()
{
    fastio;

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

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

    return 0;
}

• 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