Sort algorithm-Quick sort

First quick sort, the data structure after the study, put some sort just understand thought, has not realized, today took time to realize a bit
The idea of a quick sort is to randomly select a number from a period of time, place the element smaller than it in front of the element, place it in the back of it, and then apply the idea of split, respectively, to the two ends separated by the current element, and then recursively, because each time a number is randomly selected, So it's not stable, but it's still a good combination of speed.
Tested on HDOJ, and the efficiency of calling STL library functions is basically the same. It's still very satisfying.
Its implementation code:

#include <iostream>#include <cstdio>#include <cstring>#include <cstdlib>#include <ctime>Using namespace Std;constintN =100000;intA[n];intRandom (intNUM) {return(int) num * (double)Rand()/rand_max;}intRandominrange (intStartintEnd) {Srand( Time(NULL));returnStart + Random (end-start-1);}intPartition (intLenintStartintEnd) {int Index= Randominrange (start,end);//int Index= (start+end)/2; Swap (a[end],a[Index]);intsmall = Start-1; for(Index= start;Index< end; ++Index)    {if(a[Index] < A[end])///Swap the element smaller than the current to the front of the array {++small;        if (small! = index) swap (A[index],a[small]);    }} ++small;  Swap (a[small],a[end]); ///The element is exchanged to the middlereturnSmall;} void QuickSort (intLenintStartintEnd) {if(start = = end)return;int Index= Partition (len,start,end);if(Index> Start) QuickSort (Len,start,Index-1);if(Index< end) QuickSort (Len,Index+1, end);}intMain () {//freopen("Input.txt","R", stdin);intN while(~SCANF ("%d", &n)) { for(intI=0; i<n; i++) scanf ("%d", &a[i]); QuickSort (N,0, N-1); for(intI=0; i<n; i++)printf("%d ", A[i]); Puts""); }return 0;}

Sort algorithm-Quick sort