제출 #235288

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
235288		Knps4422	Sparklers (JOI17_sparklers)	C++14	0 / 100	5 ms	384 KiB

sparklers

//#pns thut contains thragma optimization_level 3
//#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include<bits/stdc++.h>
/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/detail/standard_policies.hpp>
using namespace __gnu_pbds;
typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update>ordset;
*/

#define fr first
#define sc second
#define vec vector
#define pb push_back
#define pii pair<int, int>
#define forn(x,y) for(int x = 1 ; x <= y ; ++x)
#define all(x) (x).begin(),(x).end()
#define fast cin.tie(0);cout.tie(0);cin.sync_with_stdio(0);cout.sync_with_stdio(0);


using namespace std;

typedef long long ll;
typedef unsigned int uint;
typedef complex<int> point;
const int nmax = 100005;
const ll linf = 1e18;
const ll mod = 998244353;
const int inf = INT_MAX;

int n, k;
double t;
double pos[nmax];

bool check(double x ){
	int l = k - 1 , r = k + 1 ;
	double sum = t;
	while( l >= 1 || r <= n ){
		if( l == 0){
			if( sum*x*2 >= (pos[r] - pos[r-1])){
				sum += t - (pos[r] - pos[r-1])/(x*2);
				r++;		
			}else{
				return 0;
			}
		}
		else if( r == n + 1){
			if( sum*x*2 >= (pos[l+1] - pos[l])){
				sum += t - (pos[l+1] - pos[l])/(x*2);
				l--;		
			}else{
				return 0;
			}
		}
		else if( pos[l+1] - pos[l] >=  pos[r] - pos[r-1]){
			if( sum*x*2 >= (pos[r] - pos[r-1])){
				sum += t - (pos[r] - pos[r-1])/(x*2);
				r++;		
			}else{
				return 0;
			}	
		}else{
			if( sum*x*2 >= (pos[l+1] - pos[l])){
				sum += t - (pos[l+1] - pos[l])/(x*2);
				l--;		
			}else{
				return 0;
			}		
		}


	}
	return (sum >= t);
}

int main(){
	fast;
	cin >> n >> k >> t;
	forn(i,n){
		cin >> pos[i];
	}
	if(pos[1] == pos[n]){cout << 0 << '\n';return 0;}
	int l = 1 , r = 1e9;
	while ( l < r){
		int mid = (l+r)>>1;
		if(check((double)mid)) r = mid;
		else l = mid+1;
	}
	cout << r << '\n';
	
}

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