reaktor-fast-track

function (input) {
  return (
    _.foldl(input, function(prevObj, char) {
      var prev = prevObj.prev,
          max = prevObj.max,
          next = prev.substr(1) + char,
          product = _.foldl(next, function(acc, num) {
            return acc * num
          })
      return {max: (max > product ? max : product), prev: next }
    }, {max: 0, prev: '00000'})
  ).max
}