Child parent rollup count

trigger GrossAmountRollUp on Opportunity (after insert, after update) {
    List<Account> accList = new List<Account>();
    List<Id> listIds = new List<Id>();
    Decimal grossTotal = 0;
    
    for(Opportunity opp: Trigger.new){
        listIds.add(opp.AccountId);
    }
    
 for(Account a: [select Name,(select id, Amount from opportunities) from Account  where id =:listIds])
    {   
       for(Opportunity o:a.opportunities){
          grossTotal  = grossTotal+o.Amount;
        }
        a.dotsquaremukesh__Gross_Amount__c = grossTotal;
        accList.add(a);
            
    }
    
    update accList;
}