Submission #256405

#	Time	Username	Problem	Language	Result	Execution time	Memory
256405		arbor	Building Bridges (CEOI17_building)	C++14	30 / 100	37 ms	2680 KiB

building

#include <bits/stdc++.h>
#define all(x) x.begin(), x.end()
using namespace std;
using ll = long long;
using pii = pair<int, int>;
const int MN = 1e5 + 5;

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)
    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()) { x->p = inf; return false; }
        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;
    }
} con;

int N, h[MN], w[MN];
ll ps[MN], dp[MN];

int main() {
    ios_base::sync_with_stdio(0), cin.tie(0);
    cin >> N;
    for (int i = 1; i <= N; i++) cin >> h[i];
    for (int i = 1; i <= N; i++) cin >> w[i], ps[i] = ps[i - 1] + w[i];
    con.add(-2 * h[1], -ps[1] + h[1] * h[1]);
    for (int i = 2; i <= N; i++) {
        dp[i] = con.query(h[i]) + h[i] * h[i] + ps[i - 1];
        con.add(-2 * h[i], dp[i] - ps[i] + h[i] * h[i]);
    }
    cout << dp[N] << '\n';
    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 0 / 30
• Subtask 3: 0 / 40