Nodejs Array Quick Sort quicksort(A, p, q)

Method Source Code

/**//from   w  w w .j av a  2 s  .  c o m
 * QuickSort Javascript implementation
 *  - Pivot: choosing the middle index of the partition
 *  - Best: nlog(n) / Average: nlog(n) / Worst: n^2
 *  - Memory: log(n) / Not stable
 *
 * @author: Sebastian Kim
 */

Array.prototype.swap = function(i, j) {
  var tmp = this[i];
  this[i] = this[j];
  this[j] = tmp;
}

function partition(A, p, q, r) {
  var pivot = A[r];
  A.swap(r, p);
  var i = p;

  for(var j = p + 1; j <= q; ++j) {
    if(A[j] <= pivot) {
      A.swap(++i, j);
    }
  }
  A.swap(p, i);

  return i;
}


function quicksort(A, p, q)
{
  if(p < q) {
    var r = Math.floor(p + (q - p) / 2); // Prevent integer overflow
    r = partition(A, p, q, r);
    quicksort(A, p, r - 1);
    quicksort(A, r + 1, q);
  }

  return A;
}

Array.prototype.quickSort = function() {
  return quicksort(this, 0, this.length - 1);
}

Related

1. quickSort(A)

   function quickSort(A) {
     if (A.length === 0) {
       return [];
     if (A.length === 1 || (A.length === 2 && A[0] === A[1])) {
       return A;
     let p = A.findBasePoint();
     let leftPart = [],
   ...
   

2. quickSort(a,start,end)

   'use strict'
   Array.prototype.showArray = function(){
       var temp = '';
       this.forEach(function(value,index){
           temp += value + " ";
       });
       if(typeof document !== "undefined"){
           document.body.innerHTML = temp;
       else{
           console.log(temp);
   };
   function partition(a,start,end){
       var i = start,j = end;
       var key = a[i];
       while(i<j){
           while(i<j && a[j] >= key){
               j--;
           if(i<j){
               var temp;
               temp = a[i];
               a[i] = a[j];
               a[j] = temp; 
           while(i<j && a[i] <= key){
               i++;
           if(i<j){
               var temp;
               temp = a[i];
               a[i] = a[j];
               a[j] = temp; 
       return i;
   function quickSort(a,start,end){
       var middle;
       if(start<end){
           middle = partition(a,start,end);
           quickSort(a,start,middle-1);
           quickSort(a,middle,end - 1);
   var a = [6,2,7,3,8,9];
   quickSort(a,0,5);
   a.showArray();
   

3. quicksort(A, p, r)

   "use strict";
   function main(A) {
       quicksort(A, 0, A.length - 1);
       console.log(A);
   function quicksort(A, p, r) {
       if (p < r) {
           var q = partition(A, p, r);
           quicksort(A, p, q - 1);
   ...
   

4. quickSort()

   var quick = function(arr) {
     if(arr.length <= 1){
       return arr;
     var pivotIndex = Math.floor(arr.length / 2);
     var pivot = arr.splice(pivotIndex, 1)[0];
     var left = [];
     var right = [];
     var same = [];
   ...
   

5. quickSort()

   Array.prototype.quickSort = function() {
     var len = this.length
     if(len > 1) {
       var pivot = this[0]
       var left = []
       var right = []
       for(var i = 1; i < len; i++) {
         if(this[i] < pivot) {
           left.push(this[i])
   ...
   

6. quickSort()

   Array.prototype.quickSort = function() {
     var len = this.length;
     if (len <= 1) {
       return this.slice(0);
     var left = [];
     var right = [];
     var mid = [this[0]];
     for (var i = 1; i < len; i++) {
   ...