Appex Triggers on Lookup relationships

hello, you can take help from this code below  :-

trigger CountContactsnew on Contact (after insert, after delete, after undelete) {

List<id> accIdList = new List<id>();
if(Trigger.isInsert || Trigger.isUndelete){
For(Contact con1 : Trigger.new){
accIdList.add(con1.accountid);
}
}
if(Trigger.isDelete){
For(Contact con1 : Trigger.old){
accIdList.add(con1.accountid);
}
}
List<Account> accUpdateList = new List<Account>();
For(Account acc : [SELECT Contact_Recs__c,(SELECT id FROM Contacts) FROM Account WHERE id =: accIdList]){
acc.Contact_Recs__c = acc.Contacts.size();
accUpdateList.add(acc);
}
update accUpdateList;
}
}