Submission #1264956

#	Time	Username	Problem	Language	Result	Execution time	Memory
1264956		btninh	Harbingers (CEOI09_harbingers)	C++20	0 / 100	60 ms	24896 KiB

harbingers

#include <bits/stdc++.h>
using namespace std;
using ll = long long;

struct Line {
    mutable ll k, m, p;
    bool operator<(const Line& o) const { return k < o.k; }
    bool operator<(ll x) const { return p < x; }
};

struct LineContainer : multiset<Line, less<>> {
    static const ll inf = LLONG_MAX;
    ll divFloor(ll a, ll b) {
        return a / b - ((a ^ b) < 0 && a % b);
    }
    bool isect(iterator x, iterator y) {
        if (y == end()) { x->p = inf; return false; }
        if (x->k == y->k) x->p = (x->m > y->m ? inf : -inf);
        else x->p = divFloor(y->m - x->m, x->k - y->k);
        return x->p >= y->p;
    }
    // add line: y = kx + m, return rollback info
    // trả về iterator nếu line này còn tồn tại, ngược lại trả về end()
    pair<iterator, vector<Line>> add(ll k, ll m) {
        auto z = insert({k,m,0}), y = z++, x = y;
        vector<Line> erased;
        while (isect(y,z)) {
            erased.push_back(*z);
            z = erase(z);
        }
        if (x != begin() && isect(--x,y)) {
            erased.push_back(*y);
            erase(y);
        }
        while ((y = x) != begin() && (--x)->p >= y->p) {
            erased.push_back(*y);
            erase(y);
        }
        return {y, erased};
    }
    ll query(ll x) {
        assert(!empty());
        auto l = *lower_bound(x);
        return l.k * x + l.m;
    }
};

int N;
vector<vector<pair<int,ll>>> adj;
vector<ll> S, V, dist, opt;
LineContainer cht;

void dfs(int u, int p) {
    if (u == 1) {
        opt[u] = 0;
    } else {
        ll best = cht.query(V[u]);
        opt[u] = S[u] + V[u] * dist[u] + best;
    }

    // thêm line của u
    auto [it, erased] = cht.add(-dist[u], opt[u]);

    for (auto [v,w] : adj[u]) if (v != p) {
        dist[v] = dist[u] + w;
        dfs(v,u);
    }

    // rollback
    if (it != cht.end()) cht.erase(it);
    for (auto &ln : erased) cht.insert(ln);
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> N;
    adj.assign(N+1, {});
    for (int i=0;i<N-1;i++) {
        int u,v; ll w; cin >> u >> v >> w;
        adj[u].push_back({v,w});
        adj[v].push_back({u,w});
    }
    S.assign(N+1,0);
    V.assign(N+1,0);
    dist.assign(N+1,0);
    opt.assign(N+1,0);

    for (int i=2;i<=N;i++) cin >> S[i] >> V[i];

    dfs(1,0);

    for (int i=2;i<=N;i++) cout << opt[i] << "\n";
}

• Subtask 1: 0 / 100