Do some code formatting on QuickSort algorithm.

Author: trekhleb

README.md

@@ -78,7 +78,7 @@ a set of rules that precisely defines a sequence of operations.
   * [Insertion Sort](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/sorting/insertion-sort)
   * [Heap Sort](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/sorting/heap-sort)
   * [Merge Sort](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/sorting/merge-sort)
-  * [Quicksort](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/sorting/quick-sort)
+  * [Quicksort](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/sorting/quick-sort) - in-place and non-in-place implementations
   * [Shellsort](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/sorting/shell-sort)
 * **Tree**  
   * [Depth-First Search](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/tree/depth-first-search) (DFS)

src/algorithms/sorting/quick-sort/QuickSort.js

@@ -1,6 +1,10 @@
 import Sort from '../Sort';
 
 export default class QuickSort extends Sort {
+  /**
+   * @param {*[]} originalArray
+   * @return {*[]}
+   */
   sort(originalArray) {
     // Clone original array to prevent it from modification.
     const array = [...originalArray];

src/algorithms/sorting/quick-sort/QuickSortInPlace.js

@@ -1,35 +1,51 @@
 import Sort from '../Sort';
 
 export default class QuickSortInPlace extends Sort {
-  /* Sorting in place avoids unnecessary use of additional memory, but modifies input array.
+  /** Sorting in place avoids unnecessary use of additional memory, but modifies input array.
    *
    * This process is difficult to describe, but much clearer with a visualization:
-   * http://www.algomation.com/algorithm/quick-sort-visualization
+   * @see: http://www.algomation.com/algorithm/quick-sort-visualization
+   *
+   * @param {*[]} originalArray
+   * @param {number} inputLowIndex
+   * @param {number} inputHighIndex
+   * @return {*[]}
    */
-  sort(originalArray, inputLow, inputHigh) {
+  sort(originalArray, inputLowIndex, inputHighIndex) {
     // Destructures array on initial passthrough, and then sorts in place.
-    const array = inputLow === undefined ? [...originalArray] : originalArray;
-    // Partition array segment and return index of last swap
-    const partition = (l, h) => {
-      const swap = (left, right) => {
-        const tempVariable = array[left];
-        array[left] = array[right];
-        array[right] = tempVariable;
+    const array = inputLowIndex === undefined ? [...originalArray] : originalArray;
+
+    /**
+     * Partition array segment and return index of last swap
+     *
+     * @param {number} lowIndex
+     * @param {number} highIndex
+     * @return {number}
+     */
+    const partition = (lowIndex, highIndex) => {
+      /**
+       * @param {number} leftIndex
+       * @param {number} rightIndex
+       */
+      const swap = (leftIndex, rightIndex) => {
+        const tempVariable = array[leftIndex];
+        array[leftIndex] = array[rightIndex];
+        array[rightIndex] = tempVariable;
       };
 
-      const pivot = array[h];
+      const pivot = array[highIndex];
       this.callbacks.visitingCallback(array[pivot]);
-      let firstRunner = l - 1;
 
-      for (let secondRunner = l; secondRunner < h; secondRunner += 1) {
+      let firstRunner = lowIndex - 1;
+      for (let secondRunner = lowIndex; secondRunner < highIndex; secondRunner += 1) {
         if (this.comparator.lessThan(array[secondRunner], pivot)) {
           firstRunner += 1;
           swap(firstRunner, secondRunner);
         }
       }
 
       if (this.comparator.lessThan(pivot, array[firstRunner + 1])) {
-        swap(firstRunner + 1, h);
+        swap(firstRunner + 1, highIndex);
       }
 
       return firstRunner + 1;
@@ -40,20 +56,21 @@ export default class QuickSortInPlace extends Sort {
      * still have to set `high`'s default within the function as we
      * don't have access to `array.length - 1` when declaring paramaters
      */
-    const low = inputLow === undefined ? 0 : inputLow;
-    const high = inputHigh === undefined ? array.length - 1 : inputHigh;
+    const lowIndex = inputLowIndex === undefined ? 0 : inputLowIndex;
+    const highIndex = inputHighIndex === undefined ? array.length - 1 : inputHighIndex;
 
     // Base case is when low and high converge
-    if (low < high) {
-      const partitionIndex = partition(low, high);
+    if (lowIndex < highIndex) {
+      const partitionIndex = partition(lowIndex, highIndex);
       /*
        * `partition()` swaps elements of the array based on their comparison to the `hi` parameter,
        * and then returns the index where swapping is no longer necessary, which can be best thought
        * of as the pivot used to split an array in a non-in-place quicksort
        */
-      this.sort(array, low, partitionIndex - 1);
-      this.sort(array, partitionIndex + 1, high);
+      this.sort(array, lowIndex, partitionIndex - 1);
+      this.sort(array, partitionIndex + 1, highIndex);
     }
+
     return array;
   }
 }