gist.quicksort

  var quickSort = function (arr) {
    if (arr.length === 0) {
      return [];
    }

    var left = [];
    var right = [];
    var pivot = arr[arr.length - 1]; // use right most value as pivot

    _.each(arr.slice(0, arr.length - 1), function (each) {
      if (each <= pivot) {
        left.push(each);
      } else {
        right.push(pivot);
      }
    });