Submission #763403

#	Time	Username	Problem	Language	Result	Execution time	Memory
763403		amunduzbaev	Radio Towers (IOI22_towers)	C++17	17 / 100	884 ms	12612 KiB

towers

#include "towers.h"

#include "bits/stdc++.h"
using namespace std;

#ifndef EVAL
#include "stub.cpp"
#endif

#define ar array
typedef int64_t ll;
//~ #define int ll

const int inf = 1e9 + 7;
const int N = 1e5 + 5;
//~ int first, mount;
//~ vector<int> a, l, r, res;
vector<ar<int, 2>> res;
vector<int> a;

struct ST{
	vector<int> tree;
	int N;
	
	ST(int N): N(N){
		tree.resize(N << 2);
	}
	
	void set(int i, int v, int lx, int rx, int x){
		if(lx == rx){
			tree[x] = v;
			return;
		}
		
		int m = (lx + rx) >> 1;
		if(i <= m) set(i, v, lx, m, x << 1);
		else set(i, v, m + 1, rx, x << 1 | 1);
		tree[x] = max(tree[x << 1], tree[x << 1 | 1]);
	}
	
	void set(int i, int v){
		set(i, v, 0, N, 1);
	}
	
	int get(int l, int r, int lx, int rx, int x){
		if(lx > r || rx < l){
			return -(N << 2);
		}
		if(lx >= l && rx <= r){
			return tree[x];
		}
		int m = (lx + rx) >> 1;
		return max(get(l, r, lx, m, x << 1), get(l, r, m + 1, rx, x << 1 | 1));
	}
	
	int get(int l, int r){
		return get(l, r, 0, N, 1);
	}
}Max(N), Min(N);

void init(int n, vector<int> h) {
	a = h;
	vector<int> pos;
	for(int i=0;i<n;i++){
		Max.set(i, a[i]);
		if((!i || a[i] < a[i - 1]) && (i + 1 == n || a[i] < a[i + 1])){
			pos.push_back(i);
		}
	}
	
	set<int> ss;
	multiset<ar<int, 2>> dif;
	
	for(int i=0;i<(int)pos.size();i++){
		if(i){
			//~ a[pos[i]] a[pos[i - 1]]
			int mx = Max.get(pos[i - 1], pos[i]);
			dif.insert({mx - a[pos[i - 1]], pos[i - 1]});
			dif.insert({mx - a[pos[i]], pos[i]});
		}
		ss.insert(pos[i]);
	}
	
	//~ for(auto x : ss){
		//~ cout<<x<<" ";
	//~ }
	//~ cout<<"\n";
	
	while(!dif.empty()){
		auto [d, i] = *dif.begin();
		res.push_back({d, i});
			
		//~ cout<<i<<" "<<d<<"\n";
		auto it = ss.lower_bound(i);
		auto R = it; R++;
		if(it == ss.begin() || R == ss.end()){
			if(it == ss.begin()){
				int mx = Max.get(*it, *R);
				dif.erase(dif.find({mx - a[*it], *it}));
				dif.erase(dif.find({mx - a[*R], *R}));
			} else {
				auto L = it; L--;
				int mx = Max.get(*L, *it);
				dif.erase(dif.find({mx - a[*it], *it}));
				dif.erase(dif.find({mx - a[*L], *L}));
			}
			ss.erase(it);
			continue;
		}
		
		auto L = it; --L;
		
		int mx = Max.get(*L, *it);
		dif.erase(dif.find({mx - a[*it], *it}));
		dif.erase(dif.find({mx - a[*L], *L}));
		
		mx = Max.get(*it, *R);
		dif.erase(dif.find({mx - a[*it], *it}));
		dif.erase(dif.find({mx - a[*R], *R}));
		
		mx = Max.get(*L, *R);
		dif.insert({mx - a[*L], *L});
		dif.insert({mx - a[*R], *R});
		
		ss.erase(it);
	}
	res.push_back({inf, *ss.begin()});
	
	//~ for(auto x : res) cout<<x[0]<<" ";
	//~ cout<<"\n";
	
	for(int i=1;i<(int)res.size();i++){
		assert(res[i - 1][0] <= res[i][0]);
	}
}

int max_towers(int l_, int r_, int d) {
	int n = a.size();
	//~ assert(l_ == 0 && r_ == n - 1);
	
	int j = lower_bound(res.begin(), res.end(), (ar<int, 2>){d, 0}) - res.begin();
	return (int)res.size() - j;
}

Compilation message (stderr)

towers.cpp: In function 'int max_towers(int, int, int)':
towers.cpp:138:6: warning: unused variable 'n' [-Wunused-variable]
  138 |  int n = a.size();
      |      ^

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