Submission #559993

#	Time	Username	Problem	Language	Result	Execution time	Memory
559993		amunduzbaev	Sparklers (JOI17_sparklers)	C++17	0 / 100	1 ms	212 KiB

sparklers

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

#define ar array
#define int long long

const int inf = 1e9 + 5;

signed main(){
	ios::sync_with_stdio(0); cin.tie(0);
	
	int n, k, t; cin>>n>>k>>t;
	
	vector<int> a(n), d(n);
	for(int i=0;i<n;i++) cin>>a[i], a[i] *= 2;
	for(int i=1;i<n;i++){
		d[i] = a[i] - a[i-1];
	}
	k--;
	
	auto check = [&](int s){
		int l = k, r = k, pos = t * s;
		while(l || r+1<n){
			int dl = inf, dr = inf;
			if(l) dl = d[l];
			if(r+1<n) dr = d[r+1];
			if(dl <= dr){
				dl /= 2;
				if(dl > pos) return false;
				pos = pos - dl + t * s, l--;
			} else {
				dr /= 2;
				if(dr > pos) return false;
				pos = pos - dr + t * s, r++;
			}
		}
		
		return true;
	};
	
	int l = 0, r = 2 * inf;
	while(l < r){
		int m = (l + r) >> 1;
		if(check(m)) r = m;
		else l = m + 1;
	}
	
	cout<<(l+1) / 2<<"\n";
}

• Subtask 1: 0 / 30
• Subtask 2: 0 / 20
• Subtask 3: 0 / 50