Quick Sort Quicksort

The first few days realized the direct insertion sort, the bubbling sort and the direct selection sort of the three basic sorts. Today we have a look at the improved algorithm for bubbling sorting, fast sorting. Record it separately, followed by merge and cardinality sorting, etc.

Quick Sort

1. Select a fulcrum the default is the first element of the array and Array[start] as a fulcrum, all values greater than the fulcrum element are placed behind the fulcrum, all values less than the fulcrum element are placed in front of the fulcrum, complete a division, return to the position of the Fulcrum index

2. Through a division to form two sequences with sequencing, [Start, index-1] and [index + 1, end] Two, in the execution of 1 until the sequence element only 1 have finished sorting

Specific explanations and notes are noted in the code comments

Quicksort.java

1 Package Com.gxf.sort;2 3 /**4 * This allows for quick sorting5 * Quick Sort is an improvement to bubble sort6 * Select an element in the array as the fulcrum, usually the first element7 * Place elements that are greater than the pivot point behind the fulcrum, placing elements smaller than the fulcrum in front of the fulcrum8 * Such a trip down, the fulcrum front is less than the fulcrum element, the fulcrum behind the greater than the Fulcrum element9 * Each trip is divided to return the position of the fulcrum, thus forming two arrays with a sort, recursively invoking two arrays respectivelyTen * until you divide only one element at a time One * @author Administrator A  * -  */ -  Public classQuickSort { the     /** - * Here is a trip to the array, which returns the position of the fulcrum in the arrays, and the default first element is the Fulcrum - * @param Rec - * @param start + * @param end - * @return +      */ A      Public intQuickSort (Rec rec[],intStartintend) { at         intFulcrum = Rec[start].key;//Fulcrum The fulcrum of the search -         inti =start; -         intj = END;//point to start and end respectively -          while(I < J) {//i==j Time to end a division -              while(I < J && Rec[j].key > Fulcrum)//find the element on the right that is smaller than the Fulcrum -j--; inRec[i].key = Rec[j].key;//move to the pivot position between the elements on the right . -              while(I < J && Rec[i].key < Fulcrum)//find the element on the left that is larger than the Fulcrum toi++; +Rec[j].key = Rec[i].key;//the left is greater than the pivot element to exchange the past -         } the         //consider the issue of equal elements here. *Rec[i].key =Fulcrum; $         returni;Panax Notoginseng     } -      the     /** + * Fast sorting of arrays A * Recursive Implementation the * @param rec +      */ -      Public voidSort (Rec rec[],intStartintend) { $         intindex; $         if(Start <end) { -index =QuickSort (REC, start, end); -Sort (REC, start, index-1); theSort (REC, index +1, end);//Note that this is going to be +1 or infinite recursion, causing the stack to overflow. -         }Wuyi     } the     /** - * @param rec Wu      */ -      Public voidsort (Rec rec[]) { AboutSort (REC,0, Rec.length-1); $     } -      -}

Rec.java

1  PackageCom.gxf.sort;2 3  Public classRec {4      Public intkey;5     6      PublicRec (intkey) {7          This. Key =key;8     }9      PublicRec () {Ten          One     } A      Public voidShowarray (Rec rec[]) { -          for(inti = 0; i < rec.length; i++){ -              theSystem.out.print (Rec[i].key + ""); -         } -     } -      PublicRec[] Getrecarray (intarray[]) { +Rec result[] =NewRec[array.length]; -          for(inti = 0; i < Array.Length; i++){ +Result[i] =NewRec (Array[i]); A         } at         returnresult; -     } -}

Test.java

1  PackageCom.gxf.sort;2 3  Public classTest {4 5      Public Static voidMain (string[] args) {6REC REC =NewRec ();7QuickSort QuickSort =NewQuickSort ();8         9         intArray[] =New int[]{0, 32, 1, 34, 54, 5, 6};TenRec array_rec[] =Rec.getrecarray (array); OneSystem.out.println ("Order before using Quick sort:"); A Rec.showarray (ARRAY_REC); -          - Quicksort.sort (ARRAY_REC); the          -SYSTEM.OUT.PRINTLN ("Use order after quick sort:"); - Rec.showarray (ARRAY_REC); -     } +  -}

PS: Here is the main reference to the data structure of the West version

Quick Sort Quicksort