归并排序
#include
#include
typedef int InfoType;
#define n 10 //假设的文件长度,即待排序的记录数目 typedef int KeyType; //假设的关键字类型
typedef struct { //记录类型
KeyType key; //关键字项
InfoType otherinfo; //其它数据项,类型InfoType依赖于具体应用而定义 } RecType;
typedef RecType SeqList[n+1]; //SeqList为顺序表类型,表中第0个单元一般用作哨兵
void Merge(SeqList R,int low,int m,int high); void MergePass(SeqList R,int length);
void main()
{
void MergeSort(SeqList R);
int i;
SeqList R;
printf("请输入欲排序的数:");
for (i=1;i<=n;i++)
scanf("%d",&R[i].key);
printf("排序前:");
for (i=1;i<=n;i++)
printf("%d ",R[i].key);
printf("\n");
MergeSort(R);
printf("排序后:");
for (i=1;i<=n;i++)
printf("%d ",R[i].key);
printf("\n");
}
void Merge(SeqList R,int low,int m,int high) { //将两个有序的子文件R[low..m]和R[m+1..high]归并成一个有序的子文件R[low..high]
int i=low,j=m+1,p=0; //置初始值
RecType *R1; //R1是局部向量,若p定义为此类型指针速度更快
R1=(RecType *)malloc((high-low+1)*sizeof(RecType));
if(!R1) //申请空间失败
{
printf("Insufficient memory available!");
exit(0);
}
while(i<=m && j<=high) //两子文件非空时取其小者输出到R1[p]上
R1[p++]=(R[i].key<=R[j].key)?R[i++]:R[j++];
while(i<=m) //若第1个子文件非空,则复制剩余记录到R1中
R1[p++]=R[i++];
while(j<=high) //若第2个子文件非空,则复制剩余记录到R1中
R1[p++]=R[j++];
for(p=0,i=low;i<=high;p++,i++)
R[i]=R1[p]; //归并完成后将结果复制回R[low..high] }
void MergePass(SeqList R,int length) { //对R[1..n]做一趟归并排序
int i;
for(i=1;i+2*length-1<=n;i=i+2*length)
Merge(R,i,i+length-1,i+2*length-1);
//归并长度为length的两个相邻的子文件
if(i+length-1