Submission #1040065

#	Time	Username	Problem	Language	Result	Execution time	Memory
1040065		mat_jur	Building Bridges (CEOI17_building)	C++17	100 / 100	63 ms	11352 KiB

building

#include <bits/stdc++.h>
using namespace std;
#ifdef DEBUG
auto&operator<<(auto &o, pair<auto, auto> p) {o << "(" << p.first << ", " << p.second << ")"; return o;}
auto operator<<(auto &o, auto x)->decltype(x.end(), o) {o<<"{"; for(auto e : x) o<<e<<", "; return o<<"}";}
#define debug(X) cerr << "["#X"]: " << X << '\n';
#else 
#define cerr if(0)cout
#define debug(X) ;
#endif
using ll = long long;
using ld = long double;
#define all(v) (v).begin(), (v).end()
#define ssize(x) int(x.size())
#define fi first
#define se second
#define mp make_pair
#define eb emplace_back

struct Line {
	bool type;
	double x;
	ll m, c;
};

bool operator<(Line l1, Line l2) {
	if (l1.type || l2.type) return l1.x < l2.x;
	return l1.m > l2.m;
}


struct CHT {
	set<Line> cht;

	bool has_prev(set<Line>::iterator it) { return it != cht.begin(); }
	bool has_next(set<Line>::iterator it) {
		return it != cht.end() && next(it) != cht.end();
	}

	double intersect(set<Line>::iterator l1, set<Line>::iterator l2) {
		return (double)(l1->c - l2->c) / (l2->m - l1->m);
	}

	void calc_x(set<Line>::iterator it) {
		if (has_prev(it)) {
			Line l = *it;
			l.x = intersect(prev(it), it);
			cht.insert(cht.erase(it), l);
		}
	}

	bool bad(set<Line>::iterator it) {
		if (has_next(it) && next(it)->c <= it->c) return true;
		return (has_prev(it) && has_next(it) &&
				intersect(prev(it), next(it)) <= intersect(prev(it), it));
	}

	void add(ll m, ll c) {
		set<Line>::iterator it;

		it = cht.lower_bound({0, 0, m, c});
		if (it != cht.end() && it->m == m) {
			if (it->c <= c) return;
			cht.erase(it);
		}

		it = cht.insert({0, 0, m, c}).first;
		if (bad(it)) cht.erase(it);
		else {
			while (has_prev(it) && bad(prev(it))) cht.erase(prev(it));
			while (has_next(it) && bad(next(it))) cht.erase(next(it));

			if (has_next(it)) calc_x(next(it));
			calc_x(it);
		}
	}

	ll query(ll h) {
		Line l = *prev(cht.upper_bound({1, (double)h, 0, 0}));
		return l.m * h + l.c;
	}
};


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

	int n;
	cin >> n;
	vector<int> h(n), w(n);
	for (int &x : h) cin >> x;
	for (int &x : w) cin >> x;

	vector<ll> pref(n);
	for (int i = 0; i < n; ++i)
		pref[i] = w[i] + (i-1 < 0 ? 0 : pref[i-1]);

	vector<ll> dp(n);

	CHT cht;

	for (int j = 0; j < n; ++j) {
		if (j > 0)
			dp[j] = ll(h[j])*h[j] + (j-1 < 0 ? 0 : pref[j-1]) + cht.query(h[j]);
		else 
			dp[j] = 0;

		cht.add(-2 * h[j], ll(h[j]) * h[j] + dp[j] - pref[j]);
	}

	cout << dp[n-1] << '\n';

	return 0;
}

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