显示合并排序的输出

Question

我希望输出只是排序后的结果而不是显示所有步骤并在选择2和选择3中得到答案。 这是我的代码：

#include <iostream>
#include <cstdio>
#include <cstdlib>
using namespace std;


struct node

{
    int data;
    struct node* next;
};
typedef struct node* nodePtr;
        nodePtr curr;
        nodePtr temp;
        nodePtr head;
        nodePtr Node;
        nodePtr counter;


void addNode(int data);
bool Empty();
struct node* SortedMerge(node* a, node* b);
void display_m(struct node* counter);
void MergeSort(struct node** Head);
void Split(node* givennumber, node** Front, node** Back);



bool Empty() {
    return head == NULL;
}


void addNode(int data ){
    nodePtr n = new node;
    n->next = NULL;
    n->data = data;

    if(!Empty()){
        curr = head;

            while(curr->next !=NULL){
                curr = curr->next;

            }
        curr->next = n;
    }
    else{
        head = n;

    }
}


void display(){
    counter = head;
    while(counter != NULL)
    {
        cout<<counter->data<<" ";
        counter = counter-> next;
    }
 cout<<endl;
}

void display_m(struct node* counter){

    while(counter != NULL)
    {
        cout<<counter->data<<" ";
        counter = counter-> next;
    }
 cout<<endl;
}

void MergeSort(struct node** Head)
{
    node* head = *Head;
    node* a;
    node* b;
    if ((head == NULL) || (head->next == NULL))
    {
        return;
    }
    Split(head, &a, &b);
    MergeSort(&a);
    MergeSort(&b);
    *Head = SortedMerge(a, b);
}


struct node* SortedMerge(struct node* a, struct node* b)
{
    node* result = NULL;
    if (a == NULL)
        return b;
    else if (b==NULL)
        return a;
    if (a->data <= b->data)
    {
        result = a;
        result->next = SortedMerge(a->next, b);
        display_m(a);
    }
    else
    {
        result = b;
        result->next = SortedMerge(a, b->next);
        display_m(b);
    }
    return result;
}




void Split(node* givennumber, node** Front, node** Back)
{
    node* fast;
    node* slow;
    if (givennumber==NULL || givennumber->next==NULL)
    {
        *Front = givennumber;
        *Back = NULL;
    }
    else
    {
        slow = givennumber;
        fast = givennumber->next;
        while (fast != NULL)
        {
            fast = fast->next;
            if (fast != NULL)
            {
                slow = slow->next;
                fast = fast->next;
            }
        }
        *Front = givennumber;
        *Back = slow->next;
        slow->next = NULL;
        display_m(*Front);
        display_m(*Back);

    }
}



int main()
{

    int i;
    char choice;
    cout << "Merge Sort Selection: " << endl;
    cout << "[1] 20 random numbers" << endl;
    cout << "[2] 200 random numbers" << endl;
    cout << "[3] 2000 random numbers" << endl;
    cin >> choice;
    cout << endl;

    switch(choice){
        case '1':
            {
            for(int i=0 ; i <20 ; i++){
            int random = rand() % 99 ;
            addNode(random);
            }
            cout << "20 Random Numbers: " ;
            display();
            cout<<"Sorting data: \n";
            MergeSort(&head);
            cout<< "\nResult: \n";
            display_m(head);
            system ("pause");
            return 0;
            }
            break;
        case '2':
            {
            for(int i=0 ; i <200 ; i++){
            int random = rand() % 99 ;
            addNode(random);
            }
            cout << "200 Random Numbers: " ;
            display();
            cout<<"Sorting data: \n";
            MergeSort(&head);
            cout<< "\nResult: \n";
            display_m(head);
            system ("pause");
            return 0;
            }
            break;
        case '3':
            {
            for(int i=0 ; i <2000 ; i++){
            int random = rand() % 99 ;
            addNode(random);
            }
            cout << "2000 Random Numbers: " ;
            display();
            cout<<"Sorting data: \n";
            MergeSort(&head);
            cout<< "\nResult: \n";
            display_m(head);
            system ("pause");
            return 0;
            }
            break;

    }

}

我期望选择2和选择3的输出如下： 随机200个数字：“未分类的200个数字” 结果：“排序了200个数字而没有显示步骤”