Question

How to merge overlapping ranges (start,end),(start,end) in Scala

Answer 1

object MergeRangesApp {

  def mergeRanges(ranges: List[(Int, Int)]): List[(Int, Int)] = {
    val sorted = ranges.sortBy(_._1)

    sorted.foldLeft(List.empty[(Int, Int)]) {
      case (Nil, range) =>
        List(range)

      case (merged @ (lastStart, lastEnd) :: rest, (start, end)) =>
        if (start <= lastEnd)
          (lastStart, math.max(lastEnd, end)) :: rest
        else
          (start, end) :: merged
    }.reverse
  }

  def main(args: Array[String]): Unit = {
    val ranges = List(
      (302, 447),
      (488, 489),
      (121, 234),
      (200, 421),
      (140, 354)
    )

    val merged = mergeRanges(ranges)
    
    println(merged)
  }
}
 
 
 
 
/*
run:
 
List((121,447), (488,489))
 
*/

 

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