Move-to-front algorithm: Difference between revisions

</pre>

=={{header|Ring}}==

<lang ring>

# Project : Move-to-front algorithm

# Date : 2018/01/13

# Author : Gal Zsolt (~ CalmoSoft ~)

# Email : <calmosoft@gmail.com>

test("broood")

test("bananaaa")

test("hiphophiphop")

func encode(s)

symtab = "abcdefghijklmnopqrstuvwxyz"

res = ""

for i=1 to len(s)

ch = s[i]

k = substr(symtab, ch)

res = res + " " + (k-1)

for j=k to 2 step -1

symtab[j] = symtab[j-1]

next

symtab[1] = ch

next

return res

func decode(s)

s = str2list( substr(s, " ", nl) )

symtab = "abcdefghijklmnopqrstuvwxyz"

res = ""

for i=1 to len(s)

k = number(s[i]) + 1

ch = symtab[k]

res = res + " " + ch

for j=k to 2 step -1

symtab[j] = symtab[j-1]

next

symtab[1] = ch

next

return right(res, len(res)-2)

func test(s)

e = encode(s)

d = decode(e)

see "" + s + " => " + "(" + right(e, len(e) - 1) + ") " + " => " + substr(d, " ", "") + nl

</lang>

Output:

<pre>

broood => (1 17 15 0 0 5) => broood

bananaaa => (1 1 13 1 1 1 0 0) => bananaaa

hiphophiphop => (7 8 15 2 15 2 2 3 2 2 3 2) => hiphophiphop