Submission #990357

#	Time	Username	Problem	Language	Result	Execution time	Memory
990357		amine_aroua	Sparklers (JOI17_sparklers)	C++17	100 / 100	63 ms	4608 KiB

sparklers

#include <bits/stdc++.h>
//#pragma GCC optimize("O3")
//#pragma GCC optimize("unroll-loops")
using namespace std;
#define int long long
#define pb push_back
#define nl '\n'
#define fore(i, y) for(int i = 0; i < y; i++)
#define forr(i, x, y) for(int i = x;i<=y;i++)
#define forn(i, y, x) for(int i = y; i >= x; i--)
const int N = 1e5 + 10;
int n , k , t;
int x[N];
bool check(vector<int> a , vector<int> b)
{
    int mx = a[0] , mn = b[0];
    int i = 1 , j = 1;
    while(true)
    {
        if(i < (int)a.size() && a[i] >= mn)
            mx = max(mx , a[i++]);
        else if(j < (int)b.size() && b[j] <= mx)
            mn = min(mn , b[j++]);
        else
            break;
    }
    return (i == (int)a.size() && j == (int)b.size());
}
bool check(int s)
{
    vector<int> a , b;
    forn(i , k , 1)
        a.pb(x[i] - 2*t*s * i);
    forr(i  , k , n)
        b.pb(x[i] - 2*t*s * i);
    if(!check(a , b))
        return 0;
    reverse(a.begin() , a.end());
    reverse(b.begin() , b.end());
    return check(a , b);
}
signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin>>n>>k>>t;
    bool acc = 1;
    forr(i , 1 , n) {
        cin >> x[i];
        if (x[i] != 0)
            acc = 0;
    }
    if(acc)
    {
        cout<<0<<nl;
        return 0;
    }
    int lo = 0 , hi = 1e10;
    while(lo + 1 < hi)
    {
        int mid = (lo + hi)/2;
        if(check(mid))
            hi = mid;
        else
            lo = mid;
    }
    cout<<hi<<nl;
}

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