Submission #1067065

#	Time	Username	Problem	Language	Result	Execution time	Memory
1067065		AdamGS	Radio Towers (IOI22_towers)	C++17	0 / 100	754 ms	12280 KiB

towers

#include "towers.h"
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(a, b) for(int a = 0; a < (b); ++a)
#define st first
#define nd second
#define pb push_back
#define all(a) a.begin(), a.end()
const ll INF=1e18+7;
const int LIM=1e5+7;
ll T[LIM], jaki[LIM], n;
set<pair<ll,ll>>S, P;
vector<pair<ll,ll>>ans;
void dodaj(int x) {
	auto it=S.lower_bound({x, -1}); ++it;
	auto a=*it;
	P.insert({abs(T[x]-T[a.st]), x});
}
void usun(int x) {
	auto it=S.lower_bound({x, -1}); ++it;
	auto a=*it;
	P.erase({abs(T[x]-T[a.st]), x});
}
void init(int _n, vector<int>_H) {
	n=_n;
	rep(i, n) T[i+1]=_H[i];
	T[0]=T[n+1]=INF;
	int akt=2;
	jaki[0]=jaki[n+1]=1;
	rep(i, n) if((T[i]<T[i+1] && T[i+1]>T[i+2]) || (T[i]>T[i+1] && T[i+1]<T[i+2])) {
		jaki[i+1]=akt;
		akt^=3;
	}
	rep(i, n+2) if(jaki[i]) S.insert({i, jaki[i]});
	auto it=S.begin();
	while(true) {
		auto it2=it; ++it2;
		if(it2==S.end()) break;
		auto a=*it;
		dodaj(a.st);
		++it;
	}
	ans.pb({0, S.size()/2});
	while(P.size()>2) {
		auto a=*P.begin();
		usun(a.nd);
		auto it=S.lower_bound({a.nd, -1});
		++it;
		auto b=*it;
		usun(b.st);
		--it; --it;
		b=*it;
		usun(b.st);
		++it;
		S.erase(it);
		it=S.lower_bound({a.nd, -1});
		S.erase(it);
		it=S.lower_bound({a.nd, -1});
		--it;
		b=*it;
		dodaj(b.st);
		ans.pb({a.st, S.size()/2});
	}
}
int max_towers(int l, int r, int d) {
	int po=0, ko=ans.size()-1;
	while(po<ko) {
		int sr=(po+ko+1)/2;
		if(ans[sr].st<=d) po=sr; else ko=sr-1;
	}
	return ans[po].nd;
}

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