trelloreversehash

reversehash.js

//https://trello.com/jobs/details?gh_jid=480058

window.letters = "acdegilmnoprstuw";

function hash(s) {
  var h = 7;
  for(var i = 0; i < s.length; i++) {
    h = h * 37 + letters.indexOf(s[i]);
  }
  return h;
}

//this is O(letters.length ^ left). It'll crash your shit.
function brutehash(s, left) {
  if(left === 0) {
    if(hash(s) === 680131659347) {
      console.log('found it: ' + s);
      return true;
    } else {
      return false;
    }
  } else {
    for(var i = 0; i < letters.length; i++) {
      if(brutehash(s + letters[i], left-1)) {
        return true;
      }
    }
    return false;
  }
}

//reversehash(930846109532517, '') = 'found: lawnmower'
//reversehash(680131659347, '') = 'found: leepadg'
function reversehash(num, result) {
  for(var i = 0; i < letters.length; i++) {
    rev = (num - i) / 37;
    //console.log('trying '+letters[i]+', rev: '+rev);
    if(rev % 1 === 0) {
      result = letters[i] + result;
      if(rev === 7) {
        console.log('found: '+result);
        return true;
      } else {
        if(reversehash(rev, result)) {
          return true;
        }
      }
    }
  }
  return false;
}