trigger UpdateAccountStatus on Contact (after insert,after update) {
 // create a list of account Id  
 List<ID> actListID = new List<Id>();
  // play a for loop on trigger.new (contact List) and check if contact account Id != null and 
  // contact status = 'finish'  
  for(Contact con:Trigger.new){
     if(con.Status__c == 'Finish'&& con.AccountID != Null){
       actListID.add(con.AccountID);
     }
  }

  
  // create a list of account to update account status  
   List<Account> lstUpdate = new List<Account>() ;
  
 // play a for loop on account and query all child records of account object where Id in actListID (trigger.New account id's) 
  for(account acc : [select id,Status__c,(select id,Status__c from contacts) from account where id IN : actListID]){
    // take a boolean flag to check if all contact Status__c finish or NOT 
	 boolean bStatusEnd = true;
    // play a for loop on account realted contacts.. 
	// and check if status__c != Finish	then make boolean flag as false
	for(contact cc : acc.contacts){
	  if(cc.Status__c != 'Finish'){
	    bStatusEnd = false;
	  }
	}
	
  // if bStatusEnd = true, means all contact status__c fields have 'Finish' value then update the account status 
  // and add account in list to update   
	if(bStatusEnd){
	   acc.Status__c = 'End';
	   lstUpdate.add(acc);
	}
	
  }
  
  //   check if lstUpdate have more then 0 records then update the account list
  if(lstUpdate.size() > 0){
    update lstUpdate;
   }
}