799A - Carrot Cakes - CodeForces Solution

#include <bits/stdc++.h>
typedef long long ll;
typedef long double ld;

#define vector<int> vi;
#define vector<ll> vll;
#define all(x) (x).begin(),(x).end()
#define pb push_back
#define SZ(x) (int)x.size()
#define ALL(x) (x).begin(),(x).end()
#define SORT(x) sort((x).begin(),(x).end())
using namespace std;

int main()
{
    int n,t,k,d,time=0;
    cin >>n>>t>>k>>d;
    int cake=n,round=t,per=k;
    for(int i=1; cake>0; i++)
    {
        time+=round;
        cake-=per;
    }
    int time2=0,time3=d;
    for(int i=1; n>0; i++)
    {
        time2+=t;
        n-=k;
        if(time2>d)
        {
            time3+=t;
            n-=k;
        }
    }
    int x=max(time2,time3);
    if(x<time) cout<<"YES"<<endl;
    else cout<<"NO"<<endl;
    return 0;
}