Submission #817848

#	Time	Username	Problem	Language	Result	Execution time	Memory
817848		Temmie	Radio Towers (IOI22_towers)	C++17	100 / 100	1833 ms	304752 KiB

towers

#include <bits/stdc++.h>

constexpr const int MXH = (int) 1e9 + 5;

struct Sparse {
	struct Item {
		int mn = MXH, mx = -MXH, anl = 0, anr = 0, mn_ind = -1;
		static Item merge(const Item& l, const Item& r) {
			return {
				std::min(l.mn, r.mn), std::max(l.mx, r.mx),
				std::max({ l.anl, r.anl, r.mx - l.mn }), std::max({ l.anr, r.anr, l.mx - r.mn }),
				l.mn < r.mn ? l.mn_ind : r.mn_ind
			};
		}
	};
	int size;
	std::vector <std::vector <Item>> bin;
	void init(const std::vector <int>& v) {
		bin.resize(17, std::vector <Item> (size = v.size()));
		for (int i = 0; i < size; i++) bin[0][i].mn = bin[0][i].mx = v[i], bin[0][i].mn_ind = i;
		for (int b = 1; b < 17; b++)
			for (int i = 0; i + (1 << (b - 1)) < size; i++)
				bin[b][i] = Item::merge(bin[b - 1][i], bin[b - 1][i + (1 << (b - 1))]);
	}
	Item query(int l, int r) {
		Item res;
		if (l >= r || l < 0 || r >= size) return res;
		for (int b = 31 - __builtin_clz(r - l), range = r - l; ~b; l += ((range >> b) & 1) << b, b--)
			if (range & (1 << b))
				res = Item::merge(res, bin[b][l]);
		return res;
	}
};

struct PNode {
	struct Item {
		int sum = 0;
		int mn = MXH, mx = -MXH;
		static Item merge(const Item& l, const Item& r) {
			return { l.sum + r.sum, std::min(l.mn, r.mn), std::max(l.mx, r.mx) };
		}
	};
	typedef std::shared_ptr <PNode> PPNode;
	Item item;
	PPNode lc = nullptr, rc = nullptr;
	PNode(const Item& _item) : item(_item) { }
	PNode(PPNode _lc, PPNode _rc) : item(Item::merge(_lc->item, _rc->item)), lc(_lc), rc(_rc) { }
	static PPNode build(int l, int r) {
		if (!(r - l - 1)) return PPNode(new PNode({ }));
		int mid = (l + r) >> 1;
		return PPNode(new PNode(build(l, mid), build(mid, r)));
	}
	static PPNode set(PPNode node, int ind, int l, int r) {
		if (!(r - l - 1)) return PPNode(new PNode({ 1, ind, ind }));
		int mid = (l + r) >> 1;
		if (ind < mid) return PPNode(new PNode(set(node->lc, ind, l, mid), node->rc));
		return PPNode(new PNode(node->lc, set(node->rc, ind, mid, r)));
	}
	Item query(int tl, int tr, int l, int r) {
		if (l >= tr || r <= tl) return { };
		if (l >= tl && r <= tr) return item;
		int mid = (l + r) >> 1;
		return Item::merge(lc->query(tl, tr, l, mid), rc->query(tl, tr, mid, r));
	}
};

int n;
std::vector <int> h;
Sparse sparse;
std::vector <std::shared_ptr <PNode>> pst;
std::map <int, int> smp;

void init(int N, std::vector <int> H) {
	n = N + 4;
	h = H;
	h.insert(h.begin(), { 0, MXH });
	h.insert(h.end(), { MXH, 0 });
	sparse.init(h);
	std::vector <std::pair <int, int>> ord(N);
	for (int i = 2; i < n - 2; i++) ord[i - 2] = { h[i], i };
	std::sort(ord.begin(), ord.end());
	std::set <int> st = { 0, n - 1 };
	std::vector <int> tmon(n);
	for (auto [hei, i] : ord) {
		auto it = st.lower_bound(i);
		tmon[i] = std::max(0, std::min(sparse.query(*prev(it) + 1, i).mx, sparse.query(i + 1, *it).mx) - hei);
		st.insert(i);
	}
	smp[MXH] = 0;
	pst.push_back(PNode::build(0, 4 * n));
	for (int i = 2; i < n - 2; i++) ord[i - 2] = { tmon[i], i };
	std::sort(ord.rbegin(), ord.rend());
	for (auto [dv, i] : ord) {
		pst.push_back(PNode::set(pst.back(), i, 0, 4 * n));
		smp[dv] = (int) pst.size() - 1;
	}
}

int max_towers(int L, int R, int D) {
	L += 2, R += 2;
	std::shared_ptr <PNode> node = pst[smp.lower_bound(D)->second];
	PNode::Item pit = node->query(L, R + 1, 0, 4 * n);
	if (!pit.sum) {
		pit.sum++;
		pit.mn = pit.mx = sparse.query(L, R + 1).mn_ind;
	}
	int ans = pit.sum;
	ans += sparse.query(L, pit.mn).anl >= D;
	ans += sparse.query(pit.mx + 1, R + 1).anr >= D;
	return ans;
}

• Subtask 1: 4 / 4
• Subtask 2: 11 / 11
• Subtask 3: 12 / 12
• Subtask 4: 14 / 14
• Subtask 5: 17 / 17
• Subtask 6: 19 / 19
• Subtask 7: 23 / 23