sidef-scripts/Encoding/run_length_encoding.sf

#!/usr/bin/ruby

# https://rosettacode.org/wiki/Run-length_encoding

func encode(str) {
    str.gsub(/(.)(\1{0,254})/, {|a,b| b.len+1 -> chr + a})
}

func decode(str) {
     var chars = str.chars
     var r = ''
     (chars.len/2 -> int).range.each { |i|
         r += (chars[2*i + 1] * chars[2*i].ord)
     }
     return r
}

var str = "WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW"
var e = encode(str)

say str
say e.dump
var d = decode(e)
say d