text: 'use strict';
  
  module.exports = quickselect;
  module.exports.default = quickselect;
  
  function quickselect(arr, k, left, right, compare) {
      quickselectStep(arr, k, left || 0, right || (arr.length - 1), compare || defaultCompare);
  };
  
  function quickselectStep(arr, k, left, right, compare) {
  
      while (right > left) {
          if (right - left > 600) {
              var n = right - left + 1;
              var m = k - left + 1;
              var z = Math.log(n);
              var s = 0.5 * Math.exp(2 * z / 3);
              var sd = 0.5 * Math.sqrt(z * s * (n - s) / n) * (m - n / 2 < 0 ? -1 : 1);
              var newLeft = Math.max(left, Math.floor(k - m * s / n + sd));
              var newRight = Math.min(right, Math.floor(k + (n - m) * s / n + sd));
              quickselectStep(arr, k, newLeft, newRight, compare);
          }
  
          var t = arr[k];
          var i = left;
          var j = right;
  
          swap(arr, left, k);
          if (compare(arr[right], t) > 0) swap(arr, left, right);
  
          while (i < j) {
              swap(arr, i, j);
              i++;
              j--;
              while (compare(arr[i], t) < 0) i++;
              while (compare(arr[j], t) > 0) j--;
          }
  
          if (compare(arr[left], t) === 0) swap(arr, left, j);
          else {
              j++;
              swap(arr, j, right);
          }
  
          if (j <= k) left = j + 1;
          if (k <= j) right = j - 1;
      }
  }
  
  function swap(arr, i, j) {
      var tmp = arr[i];
      arr[i] = arr[j];
      arr[j] = tmp;
  }
  
  function defaultCompare(a, b) {
      return a < b ? -1 : a > b ? 1 : 0;
  }
  