歸併排序C語言實現

void swap(int *a,int *b)
{
    int temp=*a;
    *a=*b;
    *b=temp;
}

void merge_array(int a[],int low,int mid,int high,int result[])
{
    int i,j,k;
    i=low;
    j=mid+1;
    k=0;
    while(i<=mid&&j<=high)
    {
        if(a[i]<a[j])
        {
            result[k]=a[i];
            i++;
            k++;
        }
        else
        {
            result[k]=a[j];
            k++;
            j++;
        }
    }
    while(i<=mid)
    {
        result[k]=a[i];
        i++;
        k++;
    }
    while(j<=high)
    {
        result[k]=a[j];
        j++;
        k++;
    }
    for(i=0;i<k;i++)    //注意 需要這一步
    {
        a[low+i]=result[i];  //low+i
    }
}

void merge_sort(int a[],int low,int high,int result[])
{
    int mid;
    if(low<high)
    {
        mid=(low+high)/2;
        merge_sort(a,low,mid,result);
        merge_sort(a,mid+1,high,result);  //mid+1
        merge_array(a,low,mid,high,result);
    }
}