Move-to-front algorithm: Difference between revisions

=={{header|Nim}}==

<lang Nim>import algorithm, sequtils, strformat

const SymbolTable = toSeq('a'..'z')

func encode(s: string): seq[int] =

var symtable: seq[char] = SymbolTable

for c in s:

let idx = symtable.find(c)

result.add idx

symtable.rotateLeft(0..idx, -1)

func decode(s: seq[int]): string =

var symtable = SymbolTable

for idx in s:

result.add symtable[idx]

symtable.rotateLeft(0..idx, -1)

for word in ["broood", "babanaaa", "hiphophiphop"]:

let encoded = word.encode()

let decoded = encoded.decode()

let status = if decoded == word: "correctly" else: "incorrectly"

echo &"'{word}' encodes to {encoded} which {status} decodes to '{decoded}'."</lang>

{{out}}

<pre>'broood' encodes to @[1, 17, 15, 0, 0, 5] which correctly decodes to 'broood'.

'babanaaa' encodes to @[1, 1, 1, 1, 13, 1, 0, 0] which correctly decodes to 'babanaaa'.

'hiphophiphop' encodes to @[7, 8, 15, 2, 15, 2, 2, 3, 2, 2, 3, 2] which correctly decodes to 'hiphophiphop'.</pre>