Created
December 31, 2015 03:15
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Majority element with Moor Voting
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| package org.sdo.alg.geeks | |
| /** | |
| * Created by dsemenov | |
| * Date: 12/30/15. | |
| */ | |
| trait MajorityElement[E] { | |
| private[this] def findCandidate(elements: List[E]): Option[E] = elements match { | |
| case head :: tail => | |
| val candidate = tail.foldLeft((head, 1)) { (context, current) => | |
| context match { | |
| case (prev, count) if prev != current => | |
| if (count - 1 == 0) (current, 1) else (prev, count - 1) | |
| case (prev, count) => (prev, count + 1) | |
| } | |
| } | |
| Some(candidate._1) | |
| case _ => None | |
| } | |
| def findMajorityElement(elements: List[E]): Option[E] = { | |
| for ( | |
| candidate <- findCandidate(elements) | |
| if elements.count(_ == candidate) >= elements.size / 2 | |
| ) yield candidate | |
| } | |
| } |
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