RosettaCodeData/Task/Knuths-algorithm-S/Nim/knuths-algorithm-s.nim

30 lines
630 B
Nim

import random
func sOfNCreator[T](n: Positive): proc(item: T): seq[T] =
var sample = newSeqOfCap[T](n)
var i = 0
result = proc(item: T): seq[T] =
inc i
if i <= n:
sample.add(item)
elif rand(1..i) <= n:
sample[rand(n - 1)] = item
sample
when isMainModule:
randomize()
echo "Digits counts for 100_000 runs:"
var hist: array[10, Natural]
for _ in 1..100_000:
let sOfN = sOfNCreator[Natural](3)
for i in 0..8:
discard sOfN(i)
for val in sOfN(9):
inc hist[val]
for n, count in hist:
echo n, ": ", count