UVa 371 - Ackermann Functions

#include<bits/stdc++.h>
#define ll long long

using namespace std;

int main()
{
 ll x, y;
 
 int j,k;
 
 while(cin>>x>>y)
 {
   if(x==0 || y==0) break;
   
   vector<ll>a;
   vector<ll>b;
   vector<ll>c;
   
  j=k=0;
  if(x>y) swap(x,y);
  
  for(ll i=x; i<=y; i++ )
  {
   
   ll ti=0;
   ll tn=i;
   
   if(i==1)
   {
    ti=3;
   }
   
   else {
    while(tn!=1)
   {
    if(tn%2==0){
      tn= tn/2;
      ti++;
    }
    else {
     tn=3*tn+1;
     ti++;
    }
   }
   }
   
   a.push_back(i);
   b.push_back(ti);
   c.push_back(ti);
   
  }
   sort(b.begin(),b.end());
  
   for(ll l=0; l<c.size(); l++)
   {
    if(b[b.size()-1]==c[l]) {
     
     cout<<"Between "<<x<<" and "<<y<<", "<<a[l];
     cout<<" generates the longest sequence of "<<b[b.size()-1]<<" values."<<endl;
     break;
    }
   }
 
 }
 return 0;
}