Map<Id,List<Opportunity>> addOppurnitieswithaccount = new Map<Id,List<Opportunity>>();

Roll up summary kind of thing.

I am just lost. 



Map<Id,List<Account>> acctsWithOpps = new Map<Id,List<Account>>();
System.debug(acctsWithOpps.values());
List<Opportunity> oppl = [SELECT Account.Name, Name FROM Opportunity WHERE Id =: acctsWithOpps.values()];
for(Opportunity opp: acctsWithOpps.values()){
    system.debug(opp.Name);
}.

Please advice.