Created
February 10, 2012 10:18
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Ensuring contiguity among pairs
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| def ensureContiguity(xs: List[(Int, Int)], acc: List[(Int, Int)] = List.empty): List[(Int, Int)] = | |
| (xs, acc) match { | |
| case (Nil, l) => l | |
| case (l, Nil) => ensureContiguity(l dropRight 1, List(l.last)) | |
| case _ => { | |
| val t = xs.last | |
| val h = acc.head | |
| if (t._2 == h._1) | |
| ensureContiguity(xs dropRight 1, t +: acc) | |
| else | |
| ensureContiguity(xs dropRight 1, t +: (t._2, h._1) +: acc) | |
| } | |
| } | |
| /* | |
| scala> ensureContiguity(List((1, 2), (2, 3), (6, 9), (10, 11))) | |
| res3: List[(Int, Int)] = List((1,2), (2,3), (3,6), (6,9), (9,10), (10,11)) | |
| scala> ensureContiguity(List((4, 9), (40, 200))) | |
| res4: List[(Int, Int)] = List((4,9), (9,40), (40,200)) | |
| scala> ensureContiguity(List.empty) | |
| res5: List[(Int, Int)] = List() | |
| scala> ensureContiguity(List((1, 2), (2, 3))) | |
| res6: List[(Int, Int)] = List((1,2), (2,3)) | |
| */ |
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