递归实现
//归并排序 递归实现
#include <iostream>
using namespace std;
#define MAXSIZE 10
// 实现归并,并把最后的结果存放到 list1里
void merging(int *list1, int list1_size , int *list2, int list2_size)
{
int i , j ,k ,m ;
int temp[MAXSIZE];
i = j = k = 0;
while( i < list1_size && j < list2_size )
{
if( list1[i] < list2[j] )
{
temp[k++] = list1[i++];
}
else
{
temp[k++] = list2[j++];
}
}
while( i < list1_size )
{
temp[k++] = list1[i++];
}
while( i < list2_size )
{
temp[k++] = list2[j++];
}
for( m=0; m < (list1_size + list2_size); m++ )
{
list1[m] = temp[m];
}
}
void MergeSort( int k[], int n )
{
if( n > 1)
{
int *list1 = k;
int list1_size = n/2;
int *list2 = k + n/2;
int list2_size = n - list1_size;
MergeSort(list1, list1_size);
MergeSort(list2, list2_size);
merging(list1, list1_size , list2, list2_size);//归并
}
}
int main()
{
int i ,a[10] = {5,2,6,0,3,9,1,7,4,8};
MergeSort(a,10);
for( i=0; i < 10 ;i++ )
{
cout << a[i];
}
cout << endl;
return 0;
}
迭代实现
//归并排序 迭代实现
#include <iostream>
#include <stdlib.h>
using namespace std;
#define MAXSIZE 10
void MergeSort( int k[], int n )
{
int i, left_min, left_max, right_min, right_max;
int *temp = (int *)malloc(n * sizeof(int));
for( i=1; i < n; i*=2 )//步长
{
for( left_min=0; left_min < n-i; left_min = right_max )
{
right_min = left_max = left_min + i ;
right_max = left_max + i;
if( right_max > n ) //不能大于元素的个数
{
right_max = n;
}
int next = 0;
while( left_min < left_max && right_min < right_max)
{
if( k[left_min] < k[right_min] )
{
temp[next++] = k[left_min++];
}
else
{
temp[next++] = k[right_min++];
}
}
while( left_min < left_max ) //如果Lmin 没有走到LMAX的位置 说明L还有元素
{
k[--right_min] = k[--left_max ]; //把L的元素放在R的头部位置
}
while( next > 0 )
{
k[--right_min] = temp[--next]; //把整个数组还原到 刚刚剩下那个最大元素的后面
}
}
}
}
int main()
{
int i ,a[10] = {5,2,6,0,3,9,1,7,4,8};
MergeSort(a,10);
for( i=0; i < 10 ;i++ )
{
cout << a[i];
}
cout << endl;
return 0;
}