Submission #880154

#	Time	Username	Problem	Language	Result	Execution time	Memory
880154		DylanSmith	Building Bridges (CEOI17_building)	C++17	100 / 100	38 ms	8276 KiB

building

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

#define pb push_back
#define sz(x) (int)x.size()
#define all(x) begin(x),end(x)
#define lb(x,y) lower_bound(all(x),y)-begin(x)

mt19937 rng;

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<>> {
    // (for doubles, use inf = 1/.0, div(a,b) = a/b)
    static const ll inf = LLONG_MAX;
    ll div(ll a, ll b) { // floored division
        return a / b - ((a ^ b) < 0 && a % b); }
    bool isect(iterator x, iterator y) {
        if (y == end()) return x->p = inf, 0;
        if (x->k == y->k) x->p = x->m > y->m ? inf : -inf;
        else x->p = div(y->m - x->m, x->k - y->k);
        return x->p >= y->p;
    }
    void add(ll k, ll m) {
        auto z = insert({k, m, 0}), y = z++, x = y;
        while (isect(y, z)) z = erase(z);
        if (x != begin() && isect(--x, y)) isect(x, y = erase(y));
        while ((y = x) != begin() && (--x)->p >= y->p)
            isect(x, erase(y));
    }
    ll query(ll x) {
        assert(!empty());
        auto l = *lower_bound(x);
        return l.k * x + l.m;
    }
};

void solve() {
    int N; cin >> N;
    vector<int> h(N), w(N);
    for (int i = 0; i < sz(h); i++) cin >> h[i];
    for (int i = 0; i < sz(w); i++) cin >> w[i];
    ll sub = 0;
    for (int i : w) sub += i;
    LineContainer lc;
    lc.add(2 * h[0], w[0] - (ll)h[0] * h[0]);
    for (int i = 1; i < N; i++) {
        ll n = -lc.query(h[i]) + (ll)h[i] * h[i] - w[i];
        if (i == N - 1) cout << (n + sub) << "\n";
        lc.add(2 * h[i], -n - (ll)h[i] * h[i]);
    }
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    rng = mt19937(chrono::steady_clock::now().time_since_epoch().count());

    solve();

    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 30 / 30
• Subtask 3: 40 / 40