데이터 구조 루틴 - 병합 정렬

#include <stdio.h>
#include <malloc.h>
#define MaxSize 20
typedef int KeyType;    //       
typedef char InfoType[10];
typedef struct          //    
{
    KeyType key;        //    
    InfoType data;      //     ,   InfoType
} RecType;              //         

void Merge(RecType R[],int low,int mid,int high)
{
    RecType *R1;
    int i=low,j=mid+1,k=0; //k R1   ,i、j    1、2    
    R1=(RecType *)malloc((high-low+1)*sizeof(RecType));  //      
    while (i<=mid && j<=high)       //  1   2         
        if (R[i].key<=R[j].key)     //  1       R1 
        {
            R1[k]=R[i];
            i++;
            k++;
        }
        else                            //  2       R1 
        {
            R1[k]=R[j];
            j++;
            k++;
        }
    while (i<=mid)                      //  1        R1
    {
        R1[k]=R[i];
        i++;
        k++;
    }
    while (j<=high)                 //  2        R1
    {
        R1[k]=R[j];
        j++;
        k++;
    }
    for (k=0,i=low; i<=high; k++,i++) // R1   R 
        R[i]=R1[k];
}

void MergePass(RecType R[],int length,int n)    //           
{
    int i;
    for (i=0; i+2*length-1<n; i=i+2*length)     //  length       
        Merge(R,i,i+length-1,i+2*length-1);
    if (i+length-1<n)                       //      ,      length
        Merge(R,i,i+length-1,n-1);          //       
}
void MergeSort(RecType R[],int n)           //           
{
    int length;
    for (length=1; length<n; length=2*length) //  log2n   
        MergePass(R,length,n);
}
int main()
{
    int i,n=10;
    RecType R[MaxSize];
    KeyType a[]= {9,8,7,6,5,4,3,2,1,0};
    for (i=0; i<n; i++)
        R[i].key=a[i];
    printf("   :");
    for (i=0; i<n; i++)
        printf("%d ",R[i].key);
    printf("
");
    MergeSort(R,n);
    printf("   :");
    for (i=0; i<n; i++)
        printf("%d ",R[i].key);
    printf("
");
    return 0;
}