Javascript Data Structure Tutorial - Javascript Quicksort

The Quicksort algorithm is one of the fastest sorting algorithms for large data sets.

The algorithm divides the list into sublists by selecting one element of the list as a pivot.

The Quicksort algorithm is best to use on large data sets.

Example

This algorithm then translates into the following JavaScript program:


function qSort(arr) //from w  w w.  j  a v  a  2  s  .co m
{ 
    if (arr.length == 0) { 
        return []; 
    } 
    var left = []; 
    var right = []; 
    var pivot = arr[0]; 
    for (var i = 1; i < arr.length; i++) { 
        if (arr[i] < pivot) { 
            left.push(arr[i]); 
        } else { 
            right.push(arr[i]); 
        } 
    } 
    return qSort(left).concat(pivot, qSort(right)); 
} 
var a = []; 
for (var i = 0; i < 10; ++i) { 
    a[i] = Math.floor((Math.random()*100)+1); 
} 
console.log(a); 
console.log(); 
console.log(qSort(a));

The code above generates the following result.