Submission #245811

#	Time	Username	Problem	Language	Result	Execution time	Memory
245811		Osama_Alkhodairy	Sparklers (JOI17_sparklers)	C++17	0 / 100	6 ms	384 KiB

sparklers

#include <bits/stdc++.h>
using namespace std;
#define finish(x) return cout << x << endl, 0
#define ll long long
#define ld long double

int n, k, T;
vector <int> x;
 
bool can(int s){
    int l, r;
    l = r = k;
    ld t = T;
    auto calc = [&](ld d){
        d /= 2;
        return t - d / s;
    };
    while(l > 0 || r < n - 1){
        ld new_t_l, new_t_r;
        if(l > 0){
            new_t_l = calc(x[l] - x[l - 1]);
        }
        else new_t_l = -1;
        if(r < n - 1){
            new_t_r = calc(x[r + 1] - x[r]);
        }
        else new_t_r = -1;
        ld mx = max(new_t_l, new_t_r);
        if(mx < 0) return 0;
        if(new_t_l == mx){
            l--;
            t = new_t_l + T;
        }
        else{
            r++;
            t = new_t_r + T;
        }
    }
    return 1;
}
int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> k >> T;
    x.resize(n);
    for(auto &i : x) cin >> i;
    k--;
    if(x.back() - x[0] == 0) finish(0);
    int l = 1, r = 1e9;
    while(l <= r){
        int mid = (l + r) / 2;
        if(can(mid)) r = mid - 1;
        else l = mid + 1;
    }
    cout << l << endl;
}

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