Submission #1074301

#	Time	Username	Problem	Language	Result	Execution time	Memory
1074301		Gromp15	Radio Towers (IOI22_towers)	C++17	37 / 100	4054 ms	4060 KiB

towers

#include <bits/stdc++.h>
#include "towers.h"
#define ll long long
#define ar array
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
using namespace std;

template<typename T> bool ckmin(T &a, const T &b ) { return a > b ? a = b, 1 : 0; }
template<typename T> bool ckmax(T &a, const T &b ) { return a < b ? a = b, 1 : 0; }

int n; vector<int> h, h2, pref;
int D;
int test(int i) {
	return (i && i+1 < n && ((h[i] > h[i-1] && h[i] > h[i+1])));
}
bool one_peak = 1;
int peak = -1;
void init(int N, std::vector<int> H) {
	n = N;
	h = H;
	h2 = H;
	sort(all(h2));
	h2.erase(unique(all(h2)), h2.end());
	for (int &x : h) x = lower_bound(all(h2), x) - h2.begin();
	pref.resize(n);
	for (int i = 0; i < n; i++) {
		pref[i] = test(i) + (i ? pref[i-1] : 0);
	}
	peak = max_element(all(h)) - h.begin();
	for (int i = peak-1; i >= 0; i--) one_peak &= h[i] < h[i+1];
	for (int i = peak+1; i < n; i++) one_peak &= h[i] < h[i-1];
}

struct seg {
	int N; vector<int> tree;
	seg(int n) : N(1<<(__lg(n)+1)), tree(2*N, -1e9) {}
	void update(int pos, int x) {
		for (int i = pos + N; i; i >>= 1) ckmax(tree[i], x);
	}
	int query(int node, int nl, int nr, int ql, int qr) {
		if (ql > nr || qr < nl) return -1e9;
		if (ql <= nl && nr <= qr) return tree[node];
		int mid = (nl+nr)/2;
		return max(query(node*2, nl, mid, ql, qr), query(node*2+1, mid+1, nr, ql, qr));
	}
	int query(int l, int r) {
		return query(1, 0, N-1, l, r);
	}
};

int Q = 0;
int max_towers(int L, int R, int _D) {
	D = _D;
	if (one_peak) {
		return 1 + (L < peak && R > peak && (max(h[L], h[R]) <= h[peak] - D));
	}
	if (Q++ == 0) {
		const int N = sz(h2);
		seg st0(N), st1(N); 
		for (int i = L; i <= R; i++) {
			auto it = lower_bound(all(h2), h2[h[i]] + D);
			if (it != h2.end()) {
				st1.update(h[i], st0.query(it - h2.begin(), N - 1) + 1);
			}
			auto it2 = upper_bound(all(h2), h2[h[i]] - D);
			if (it2 != h2.begin()) {
				it2--;
				st0.update(h[i], st1.query(0, it2 - h2.begin()));
			}
			st1.update(h[i], 1);
		}
		return st1.query(0, N-1);
	}
	if (D == 1) {
		return pref[R] - (L ? pref[L-1] : 0) + 1 - test(L) - test(R) + (L == R ? test(L) : 0);
	}
	int ans = 1;
	set<int> SL, SR;
	for (int i = L+1; i <= R-1; i++) if (h[i] > h[i-1] && h[i] > h[i+1]) {
		int l = -1, r = -1;
		for (int j = i-1; j >= L; j--) {
			if (h2[h[i]] - D >= h2[h[j]]) { 
				if (SL.count(j)) break;
				l = j;
			}
		}
		for (int j = i+1; j <= R; j++) {
			if (h2[h[i]] - D >= h2[h[j]]) { 
				if (SR.count(j)) break;
				r = j;
			}
		}
		if (~l && ~r) {
			ans++;
			SL.insert(l);
			SR.insert(r);
		}
	}
	return ans;
}

• Subtask 1: 0 / 4
• Subtask 2: 11 / 11
• Subtask 3: 12 / 12
• Subtask 4: 14 / 14
• Subtask 5: 0 / 17
• Subtask 6: 0 / 19
• Subtask 7: 0 / 23