链表的归并排序

链表的归并排序类比于数组的归并排序，区别在于需要单独编写寻找中间结点的算法。给出实际代码：

#include <iostream>
using namespace std;

// 结点的定义
struct Node {
    int data;
    struct Node* link;
    Node (int d = 0, struct Node* p = nullptr) {
        data = d;
        link = p;
    }
};

// 处理2个递增的链表数据, len是元素的个数
void Merge(Node* head1, Node* head2, int len1, int len2) {
    int* num = new int[len1 + len2];
    int n1 = 0, n2 = 0, n = 0;
    Node* p1 = head1, *p2 = head2;
    while(n1 < len1 && n2 < len2) {
        if(p1->data < p2->data) {
            num[n++] = p1->data;
            p1 = p1->link;
            ++n1;
        } else {
            num[n++] = p2->data;
            p2 = p2->link;
            ++n2;
        }
    }
    while(n1 < len1) {
        num[n++] = p1->data;
        p1 = p1->link;
        ++n1;
    }
    while(n2 < len2) {
        num[n++] = p2->data;
        p2 = p2->link;
        ++n2;
    }
    p1 = head1;
    for(int i = 0; i < len1 + len2; ++i) {
        p1->data = num[i];
        p1 = p1->link;
    }
    delete[] num;
}

// 寻找中点
Node* Middle(Node* head, int len) {
    int m = len / 2;
    Node* mid = head;
    while(m--) {
        mid = mid->link;
    }
    return mid;
}

// 递归地归并排序
void MergeSort(Node* head, int len) {
    if(len <= 1) {
        return;
    }
    Node* mid = Middle(head, len);
    int len1 = len / 2;
    int len2 = len - len1;
    MergeSort(head, len1);
    MergeSort(mid, len2);
    Merge(head, mid, len1, len2);
}

// 尾插法建立带有头结点的链表
Node* Create_Head_TailInsert(int n) {
    if(n < 0) {
        return nullptr;
    }
    Node* head = new Node;
    Node* pre = head;
    while(n--) {
        int t;
        cin >> t;
        Node* p = new Node(t);
        pre->link = p;
        pre = p;
    }
    return head;
}

// 输出函数
void Print_Head(Node* head) {
    Node* p = head->link;
    while(p != nullptr) {
        cout << p->data << " ";
        p = p->link;
    }
}

int main() {
    int n;
    cin >> n;  // 输入元素的个数
    Node* head = Create_Head_TailInsert(n);
    MergeSort(head->link, n);
    Print_Head(head);
    return 0;
}