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Kolakoski sequence: Difference between revisions
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[1, 3, 3, 3, 2, 2, 2, 1, 1, 1, 1, 1, 3, 3, 2, 2, 1, 1, 3, 2, 1, 1, 1, 1, 3, 3, 3, 2, 2, 1]
Possible Kolakoski sequence? False</pre>
=={{header|Nim}}==
{{trans|Kotlin}}
<lang Nim>template nextInCycle(a: openArray[int]; index: Natural): int =
a[index mod a.len]
#---------------------------------------------------------------------------------------------------
func kolakoski(a: openArray[int]; length: Positive): seq[int] =
result.setLen(length)
var i, k = 0
while true:
result[i] = a.nextInCycle(k)
if result[k] > 1:
for j in 1..<result[k]:
inc i
if i == length: return
result[i] = result[i - 1]
inc i
if i == length: return
inc k
#---------------------------------------------------------------------------------------------------
func possibleKolakoski(a: openArray[int]): bool =
var
rle: seq[int]
prev = a[0]
count = 1
for i in 1..a.high:
if a[i] == prev:
inc count
else:
rle.add count
count = 1
prev = a[i]
# No point adding final 'count' to rle as we're not going to compare it anyway.
for i, val in rle:
if val != a[i]: return false
result = true
#———————————————————————————————————————————————————————————————————————————————————————————————————
when isMainModule:
import sequtils, strformat
const
Ias = [@[1, 2], @[2, 1], @[1, 3, 1, 2], @[1, 3, 2, 1]]
Lengths = [20, 20, 30, 30]
for (length, ia) in zip(Lengths, Ias):
let kol = ia.kolakoski(length)
echo &"First {length} members of the sequence generated by {($ia)[1..^1]}:"
echo ($kol)[1..^1]
let s = if kol.possibleKolakoski(): "Yes" else: "No"
echo "Possible Kolakoski sequence? " & s & '\n'</lang>
{{out}}
<pre>First 20 members of the sequence generated by [1, 2]:
[1, 2, 2, 1, 1, 2, 1, 2, 2, 1, 2, 2, 1, 1, 2, 1, 1, 2, 2, 1]
Possible Kolakoski sequence? Yes
First 20 members of the sequence generated by [2, 1]:
[2, 2, 1, 1, 2, 1, 2, 2, 1, 2, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2]
Possible Kolakoski sequence? Yes
First 30 members of the sequence generated by [1, 3, 1, 2]:
[1, 3, 3, 3, 1, 1, 1, 2, 2, 2, 1, 3, 1, 2, 2, 1, 1, 3, 3, 1, 2, 2, 2, 1, 3, 3, 1, 1, 2, 1]
Possible Kolakoski sequence? Yes
First 30 members of the sequence generated by [1, 3, 2, 1]:
[1, 3, 3, 3, 2, 2, 2, 1, 1, 1, 1, 1, 3, 3, 2, 2, 1, 1, 3, 2, 1, 1, 1, 1, 3, 3, 3, 2, 2, 1]
Possible Kolakoski sequence? No</pre>
=={{header|Perl}}==
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