Submission #1117574

#	Time	Username	Problem	Language	Result	Execution time	Memory
1117574		vjudge1	Building Bridges (CEOI17_building)	C++17	100 / 100	51 ms	9808 KiB

building

#include <bits/stdc++.h>
#define pb push_back
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define f first
#define s second

using namespace std;
using ll = long long;
using pii = pair <int, int>;
const int N = 1e5 + 5;
const ll inf = 1e18;

int n, h[N], w[N];
ll dp[N], p[N];

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;
	}
};

int main() {
	ios :: 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];
		dp[i] = inf;
		p[i] = p[i - 1] + w[i];
	}
	dp[1] = 0;
	LineContainer l;
	l.add(h[1], -(dp[1] - p[1] + h[1] * 1ll * h[1]));
	for (int i = 2; i <= n; ++i) {
		dp[i] = p[i - 1] + -l.query(2 * h[i]) + h[i] * 1ll * h[i];
		l.add(h[i], -(dp[i] - p[i] + h[i] * 1ll * h[i]));
	}
	cout << dp[n];
	return 0;
}

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