java - Reducing time complexity -


i have list of objects contains statusenum. now, want return objects falls under specific list of provided statuses.

a simple solution loop on list of objects , loop on provided list of statusenums ... work however, make time complexity of o(n)^2. there way reduce o(n) ?

i can't change map. other solution think of maintaining map based on statusenums key increase space complexity lot.

edit

  • i had hashmap of objects (which said list)

here code came others ... 

public list<myobjects> getobjectsbasedoncriteria (list<objectstatus> statuses, string secondcriteria){     enumset<objectstatus> enumset = enumset.copyof(statuses);     (map.entry<long, myobject> objentry : myobjs.entryset()){         myobjects obj = objentry.getvalue();         if (enumset.contains(obj.getstatus()) && obj.equals(secondcriteria)){         ...         }     } }

use set hold statusenums (probably enumset), , check if each instance's status in set using set.contains(object.getstatus()), or whatever.

lookups in enumset , hashset o(1), solution linear (assuming 1 status per object). enumset.contains more efficient hashset.contains enum values; however, choice irrelevant overall time complexity.


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