trigger contactAccountTrigger on Account (after update) {
   Set<Id> accountIds = new Set<Id>();
   List<Contact> contactList1 = new List<Contact>();
    //System.debug('1st Loop- Outside');
    for(Account acc: Trigger.new){
        Account oldAccount = Trigger.oldMap.get(acc.ID);

                       System.debug('1st Loop- inside');
                    accountIds.add(acc.id);


    }//End of Loop
 //System.debug('2nd Loop- Outside');
    If(accountIds.size()>0){
         Map<Id,Account> mapAccount = new Map<Id,Account> ([select id,Tier__c,Type, (select id,Account_Tier__c,Account_Type__c from contacts ) from account where id in :accountIds ]);
         List<Contact> contactList = new List<Contact>();
        for(account acc :Trigger.new)
        {
            //Account oldAccount = Trigger.oldMap.get(acc.ID);


                If(mapAccount.containsKey(acc.id))
                {
                    Account accObj = mapAccount.get(acc.id);
                    List<Contact> lstCont = accObj.contacts;
                    for(contact c:lstCont)
                          {
                           c.Account_Tier__c=acc.Tier__c;
                           c.Account_Type__c = acc.Type;
                           contactList.add(c);
                          }//end of for loop
                        System.debug('2nd Loop- Inside');
                     }

        } //end of Acc1 for loop

          if(contactList.size()>0)
        {
           update contactList1;
        }

    }// End of accountIds.size()

  }//End of trigger