插入-归并排序&&普通归并排序

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
#define K 10

const int MAXN = 10000000;

int N;
int x[MAXN],y[MAXN];

void insert_sort(int a[],int l,int r)
{
    int key;
    for (int i = l + 1; i <= r; i++)
    {
        key = a[i];
        for (int j = i - 1; a[j] > key && j >= l; j--)
            a[j + 1] = a[j];
        a[j + 1] = key;
    }
}

void merge(int a[],int l,int m,int r)
{
    int n1 = m - l + 1;
    int n2 = r - m;
    int *t1,*t2;
    t1 = (int *)malloc(n1 * sizeof(int));
    t2 = (int *)malloc(n2 * sizeof(int));
    
    int i,j,k;
    for ( i = 0,k = l; i < n1; i++,k++)
        t1[i] = a[k];
    for ( j = 0,k = m + 1; j < n2; j++,k++)
        t2[j] = a[k];

    i = j = 0;
    for ( k = l; k <= r; k++)
    {
        if ( t1[i] <= t2[j] )
        {
            a[k] = t1[i];
            i++;
            if ( i == n1 )
            {
                k++;
                for ( ; j < n2; j++,k++)
                    a[k] = t2[j];
                break;
            }
        }
        else
        {
            a[k] = t2[j];
            j++;
            if ( j == n2 )
            {
                k++;
                for ( ; i < n1; i++,k++)
                    a[k] = t1[i];
                break;
            }
        }
    }

    free(t1);
    free(t2);
}

void merge_sort1(int a[],int l,int r)
{
    if ( r - l + 1 <= K )
    {
        insert_sort(a,l,r);
        return;
    }
    int mid = ( l + r ) / 2;
    merge_sort1(a,l,mid);
    merge_sort1(a,mid + 1,r);
    merge(a,l,mid,r);
}

void merge_sort2(int a[],int l,int r)
{
    if ( l < r )
    {
        int mid = ( l + r ) / 2;
        merge_sort2(a,l,mid);
        merge_sort2(a,mid + 1,r);
        merge(a,l,mid,r);
    }
}

int main()
{
    srand(time(NULL));
    scanf("%d",&N);
    
    for (int i = 0; i < N - 1; i++)
    {
        x[i] = rand() % 100000;
        y[i] = x[i];
    }

    int begin = clock();
    merge_sort1(x,0,N - 1);
    int end = clock();
    printf("insert & merge : total time of sorting : %lf\n",(double)( end - begin ) / CLOCKS_PER_SEC);

    begin = clock();
    merge_sort2(y,0,N - 1);
    end = clock();
    printf("merge : total time of sorting : %lf\n",(double)( end - begin ) / CLOCKS_PER_SEC);

    return 0;
}