归并排序
输入:待排序数据序列
功能要求:输出每步骤排序情况;希望能进行排序方向的选择(从大到小或从小到大)
#include<stdio.h>
#include<stdlib.h>
//归并排序
//----从小到大
void Merge_up(int* src,int* des,int low,int mid,int high)
{
int i = low;
int j = mid+1;
int k = low;
//比较两个有序序列中的元素,将较小的元素插入到des中
while((i<=mid)&&(j<=high))
{
if(src[i] < src[j])
{
des[k++] = src[i++];
}
else
{
des[k++] = src[j++];
}
}
//将src序列中剩余的元素复制到des中
//这两个语句只可能执行其中一个
while(i<=mid)
{
des[k++] = src[i++];
}
while(j<=high)
{
des[k++] = src[j++];
}
}
//将该排序算法封装起来
void MSort_up(int* src,int* des,int low,int high,int max)
{
int mid = 0;
int* space = (int*)malloc(sizeof(int)*max);
if(low==high)
{
des[low] = src[low];
}
else
{
mid = (low+high) / 2;
if(space!=NULL)
{
MSort_up(src,space,low,mid,max);//左边递归排序
MSort_up(src,space,mid+1,high,max);//右边递归排序
Merge_up(space,des,low,mid,high);//左右序列归并
}
free(space);
}
}
void sort_merge_up(int* a,int len)
{
MSort_up(a,a,0,len-1,len);
}
//----从大到小
void Merge_down(int* src,int* des,int low,int mid,int high)
{
int i = low;
int j = mid+1;
int k = low;
while((i<=mid)&&(j<=high))
{
if(src[i] > src[j])
{
des[k++] = src[i++];
}
else
{
des[k++] = src[j++];
}
}
while(i<=mid)
{
des[k++] = src[i++];
}
while(j<=high)
{
des[k++] = src[j++];
}
}
void MSort_down(int* src,int* des,int low,int high,int max)
{
int mid = 0;
int* space = (int*)malloc(sizeof(int)*max);
if(low==high)
{
des[low] = src[low];
}
else
{
mid = (low+high) / 2;
if(space!=NULL)
{
MSort_down(src,space,low,mid,max);
MSort_down(src,space,mid+1,high,max);
Merge_down(space,des,low,mid,high);
}
free(space);
}
}
void sort_merge_down(int* a,int len)
{
MSort_down(a,a,0,len-1,len);
}
int main()
{
int num;
int sel;
printf("请输入排序的元素的个数:");
scanf("%d",&num);
int i;
int *arr = (int *)malloc(num*sizeof(int));
printf("请依次输入这%d个元素(必须为整数):",num);
for(i=0;i<num;i++)
scanf("%d",arr+i);
printf("选择归并排序的顺序:从小到大为1,从大到小为2:");
scanf("%d",&sel);
//行排序方向的选择(从大到小或从小到大)
switch(sel){
case 1:
printf("归并排序后的顺序:");
sort_merge_up(arr,num);
for(i=0;i<num;i++)
printf("%d ",arr[i]);
printf("\n");
free(arr);
arr = 0;
break;
case 2:
printf("归并排序后的顺序:");
sort_merge_down(arr,num);
for(i=0;i<num;i++)
printf("%d ",arr[i]);
printf("\n");
free(arr);
arr = 0;
break;
}
return 0;
}