inprooog thing

alphabet = {} -- optimized use of an alphabet
alphabet["a"] = "a";alphabet["b"] = "b";alphabet["c"] = "c";alphabet["d"] = "d";alphabet["e"] = "e";alphabet["f"] = "f";alphabet["g"] = "g";alphabet["h"] = "h";alphabet["i"] = "i";alphabet["j"] = "j";alphabet["k"] = "k";alphabet["l"] = "l";alphabet["m"] = "m";alphabet["n"] = "n";alphabet["o"] = "o";alphabet["p"] = "p";alphabet["q"] = "q";alphabet["r"] = "r";alphabet["s"] = "s";alphabet["t"] = "t";alphabet["u"] = "u";alphabet["v"] = "v";alphabet["w"] = "w";alphabet["x"] = "x";alphabet["y"] = "y";alphabet["z"] = "z"

input = "Compress this: AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
output = ""
last = ""
lastn = 0

-- Compression:
print("Input: "..input)
print("Compressing...")
for i=1,#input do
    if last == "" then
        last = string.sub(input,i,i)
        lastn = i
    end

    if last ~= string.sub(input,i,i) or i == #input then
        local fricc = string.sub(input,lastn,i-1)
        output = output..last..#fricc
        last = string.sub(input,i,i)
        lastn = i
    end
end
print("\nCompressed: "..output)
-- Decompression
function isNumber(x)
    local numbers = {}
    numbers["1"] = "1";numbers["2"] = "2";numbers["3"] = "3";numbers["4"] = "4";numbers["5"] = "5";numbers["6"] = "6";numbers["7"] = "7";numbers["8"] = "8";numbers["9"] = "9";numbers["0"] = "0"
    if numbers[x] ~= nil then
        return true
    else
        return false
    end
end

function split(x)
    local tab = {}
    for i=1,#x do
        local num = string.sub(x,i,i)
        for k=1,#x-i do
            num = num.."0"
        end
        if tonumber(num) ~= 0 then
--          if num ~= "50" and num ~= "5" and num ~= "500" then
                local numberofzeros = #num-1
                for i=1,tonumber(string.sub(num,1,1)) do
                   local newnum = 1
                   for i=1,numberofzeros do
                       newnum = newnum.."0"
                   end
                   table.insert(tab,tonumber(newnum))
                end
--          end
        end
    end
    return tab
end

--print(kek("125"))

local last = 0
local let = ""
local output2 = ""
local num = 0
local don = false
for i=1,#output do
    if i == 1 then
        last = 1
        let = string.sub(output,i,i)
    end
    if i ~= 1 and isNumber(string.sub(output,i,i)) == true and don == false then
        for k=i,#output do
            if isNumber(string.sub(output,k,k)) == false or k == #output then
                if k == #output then
                    num = k
                else
                    num = k-1
                end
                break
            end
        end
        local numm = string.sub(output,i,num)
        local numm2 = split(numm)
        local numm3 = 0
        for i=1,#numm2 do
            numm3 = numm3 + numm2[i]
        end
        for k=1,numm3 do
            output2 = output2..let
        end
        don = true
    elseif i ~= 1 and isNumber(string.sub(output,i,i)) == false and don == true then
        last = i
        let = string.sub(output,i,i)
        don = false
    end
end
output2 = output2..string.sub(output2,#output2,#output2) -- add the missing piece
print("Decompressed: "..output2)

if output2 == input then
    print("\n✓ Decompressed and Input remained the same")
else
    print("\n✗ Decompressed and Input are different, please look for errors.")
end