#!/usr/bin/env lua

--[[
Challenge 102

TASK #2 > Hash-counting String
Submitted by: Stuart Little

You are given a positive integer $N.

Write a script to produce Hash-counting string of that length.

The definition of a hash-counting string is as follows:
- the string consists only of digits 0-9 and hashes, '#'
- there are no two consecutive hashes: '##' does not appear in your string
- the last character is a hash
- the number immediately preceding each hash (if it exists) is the position
of that hash in the string, with the position being counted up from 1

It can be shown that for every positive integer N there is exactly one such
length-N string.
Examples:

(a) "#" is the counting string of length 1
(b) "2#" is the counting string of length 2
(c) "#3#" is the string of length 3
(d) "#3#5#7#10#" is the string of length 10
(e) "2#4#6#8#11#14#" is the string of length 14
--]]

function hash_counting(n)
    local out, i = '', n
    while i > 0 do
        p = i
        out = '#'..out
        i = i - 1
        while i > 0 and p ~= 0 do
            out = tostring(p % 10)..out
            i = i - 1
            p = math.floor(p / 10)
        end
    end
    return out
end

print(hash_counting(tonumber(arg[1])))