Submission #1225718

#	Time	Username	Problem	Language	Result	Execution time	Memory
1225718		siewjh	Sparklers (JOI17_sparklers)	C++20	0 / 100	0 ms	468 KiB

sparklers

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int MAXN = 100005;
const ll inf = 1e18;
ll pos[MAXN], T;
int N, K; 
ll cdiv(ll a, ll b){
	return (a + b - 1) / b;
}
bool test(ll v){
	int l = K, r = K;
	while (l != 1 || r != N){
		ll ld = pos[r] - pos[l - 1], rd = pos[r + 1] - pos[l], spt = T * (r - l + 1);
		if (ld < rd){
			if (cdiv(ld, 2 * v) > spt) return 0;
			l--;
		}
		else{
			if (cdiv(rd, 2 * v) > spt) return 0;
			r++;
		}
	}
	return 1;
}
int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cin >> N >> K >> T;
	for (int i = 1; i <= N; i++) cin >> pos[i];
	pos[0] = -inf; pos[N + 1] = inf;
	ll lo = 1, hi = 1e9, ans;
	while (lo <= hi){
		ll m = (lo + hi) >> 1;
		if (test(m)){
			ans = m; hi = m - 1;
		}
		else lo = m + 1;
	}
	cout << ans;
}

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