This is a solution for the coding challenge included in this job posting from Fog Creek Software: http://www.fogcreek.com/jobs/dev/

fogcreek_cracker.js

function crack (hash, n) {
  var letters = "acdegilmnoprstuw";
  var cracked = '';
  while (n>0) {
    var mod = hash % 37;
    hash = (hash-mod)/37;
    if (mod < 0 || mod >= letters.length)
      throw "invalid hash!";
    cracked = letters[mod] + cracked;
    n--;
  }
  
  if (hash != 7)
    throw "invalid hash!";

  return cracked;
}

// leepadg
console.log(crack(680131659347, 7));

// promenade
console.log(crack(945924806726376, 9));

try {
  // invalid hash
  console.log(crack(945924806726389, 9)); 
} catch (e) {
  console.log(e);
}

try {
  // invalid hash (n should be 7)
  console.log(crack(680131659347, 10));
} catch (e) {
  console.log(e);
}

try {
  // invalid hash (n should be 9)
  console.log(crack(945924806726376, 10));
} catch (e) {
  console.log(e);
}

problem.txt

Find a 9 letter string of characters that contains only letters from

acdegilmnoprstuw

such that the hash(the_string) is

945924806726376

if hash is defined by the following pseudo-code:

Int64 hash (String s) {
  Int64 h = 7
  String letters = "acdegilmnoprstuw"
  for(Int32 i = 0; i < s.length; i++) {
    h = (h * 37 + letters.indexOf(s[i]))
  }
  return h
}

For example, if we were trying to find the 7 letter string where hash(the_string) was 680131659347, the answer would be "leepadg".