Quick ordering of JavaScript recursion

1. Quick Sorting ideas

(1) In the dataset, select an element as the "datum" (pivot).

(2) All elements smaller than "datum" are moved to the left of "datum", and all elements that are greater than "datum" are moved to the right of "datum".

(3) for the two subsets to the left and right of the Datum, repeat the first and second steps until there is only one element left in all the subsets.

2. Digital array sequencing Step analysis

(1) original array [23,4,16,49,34,86,801]

(2) Determine the middle position, the original array is divided into half [23,4,16,34] 49 [86,801]

(3) The left half and the right half of the array to do the above Operation 4 [23,16,34] 49 86 [801]

(4) Repeat Part III 4 16 [23,34] 49 86 801

(5) 4 16 23 [34] 49 86 801

(6) 4 16 23 34 49 86 801

3. Implementation of JavaScript based on recursive thinking

function QuickSort (arr) {  if (arr.length <= 1) {    ///length less than 1 returns directly to    arr;  }  var pivotindex = Math.floor (ARR.LENGTH/2);    Rounding up, take the middle position  var pivot  = Arr[pivotindex]; Take the middle value  var less = array (), greater = Array (), and for (var i = 0; i < arr.length; i++) {    if (i!=pivotindex) {if (Arr[i] >= pivot)　　{              greater. Push (Arr[i]);　　Right half}else {less              . push (Arr[i]);　　Left Half}}}  return QuickSort (less). Concat ([Pivot],quicksort (greater)); Recursive invocation}

Manipulating a JavaScript array can also remove intermediate elements and eliminate the intermediate element directly, so that you can make a few judgments when traversing.

var pivotindex = Math.floor (ARR.LENGTH/2), var pivot = Arr.splice (pivotindex, 1) [0];

　　

for (var i = 0; i < arr.length; i++) {if (Arr[i] >= pivot) {              greater. Push (Arr[i]);　　Right half}else {less              . push (Arr[i]); Left Half}}

　　

Quick ordering of JavaScript recursion