merge-sort（合并排序）

#ifndef _MERGE_H_#define _MERGE_H_template< class T >void merge( T* lpFinal, int iStart, int iMid, int iEnd ){int n1 = iMid - iStart + 1;int n2 = iEnd - iMid;T * lpFore = new T[ n1 ];T * lpRear = new T[ n2 ];//拆分出的子数组for( int index = 0; index < n1; ++index ){lpFore[ index ] = lpFinal[ iStart + index ];}for( int index = 0; index < n2; ++index ){lpRear[ index ] = lpFinal[ iMid + index + 1 ];}//数组末尾不使用哨兵元素int k = iStart;//结果数组计数int i = 0;//fore数组计数int j = 0;//rear数组计数for( ; k <= iEnd ; ++k ){if( lpFore[ i ] <= lpRear[ j ] ){lpFinal[ k ] = lpFore[ i ];if( ++i == n1 ){++k;for( ;j < n2; ++j, ++k ){lpFinal[ k ] = lpRear[ j ];}break;}}else{lpFinal[ k ] = lpRear[ j ];if( ++j == n2 ){++k;for( ;i < n1; ++i, ++k ){lpFinal[ k ] = lpFore[ i ];}break;}}}delete[] lpFore;delete[] lpRear;}#endif

#ifndef _MERGESORT_H_#define _MERGESORT_H_#include"merge.h"template< class T >void mergesort( T* lpFinal, int iStart, int iEnd ){if( iEnd > iStart ){int iMid = ( iStart + iEnd ) / 2;mergesort( lpFinal, iStart, iMid );mergesort( lpFinal, iMid + 1, iEnd );merge( lpFinal, iStart, iMid, iEnd );}}#endif

#include<iostream>using namespace std;#include<conio.h>#include"mergesort.h"int main(){int a[ 8 ] ={ 2, 89, 56, 45, 77, 4, 6, 5 };for( int i = 0; i < 8; ++i ){cout<<a[ i ]<<" ";}cout<<endl;mergesort( a, 0, 7 );for( int i = 0; i < 8; ++i ){cout<<a[ i ]<<" ";}getch();return 0;}