halfway part 2

Exam/IKT203Exam/Portfolio/SharedLib/TLinkedList.cpp

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+#include "TLinkedList.h"
+#include <iostream>
+
+TLinkedList::~TLinkedList()
+{
+    const Node* cur = head;
+    while (cur) {
+        const Node* next = cur->next;
+        delete cur;
+        cur = next;
+    }
+}
+
+void TLinkedList::Append(const TPerson& person)
+{
+    Node* newNode = new Node(person);
+    if (size == 0) {
+        head = tail = newNode;
+    } else {
+        tail->next = newNode;
+        tail = newNode;
+    }
+    size++;
+}
+
+void TLinkedList::Prepend(const TPerson& person)
+{
+    Node* newNode = new Node(person);
+    if (size == 0) {
+        head = tail = newNode;
+    } else {
+        newNode->next = head;
+        head = newNode;
+    }
+    size++;
+}
+
+void TLinkedList::InsertAtIndex(const int index, const TPerson& person)
+{
+    if (index < 0 || index > size) {
+        std::cout << "Index out of range\n";
+        return;
+    }
+
+    if (index == 0) {
+        Prepend(person);
+        return;
+    }
+    if (index == size) {
+        Append(person);
+        return;
+    }
+
+    Node* prev = head;
+    for (int i = 0; i < index - 1; ++i)
+        prev = prev->next;
+
+    Node* newNode = new Node(person);
+    newNode->next = prev->next;
+    prev->next = newNode;
+    size++;
+}
+
+void TLinkedList::Remove(const int index)
+{
+    if (index < 0 || index >= size)
+        return;
+
+    if (index == 0) {
+        const Node* oldHead = head;
+        head = head->next;
+        if (size == 1)
+            tail = nullptr;
+        delete oldHead;
+        size--;
+        return;
+    }
+
+    Node* prev = head;
+    for (int i = 0; i < index - 1; ++i)
+        prev = prev->next;
+
+    const Node* toDelete = prev->next;
+    prev->next = toDelete->next;
+    if (toDelete == tail)
+        tail = prev;
+    delete toDelete;
+    size--;
+}
+
+TPerson TLinkedList::GetAtIndex(const int index) const
+{
+    if (index < 0 || index >= size) {
+        std::cout << "Index out of range\n";
+        // return dummy
+        return {"N/A", "N/A", GUEST};
+    }
+
+    Node* cur = head;
+    for (int i = 0; i < index; ++i)
+        cur = cur->next;
+
+    return cur->person;
+}
+
+void TLinkedList::MergeSortSplit(Node *source, Node **front, Node **back)
+{
+    if (source == nullptr || source->next == nullptr) {
+        *front = source;
+        *back = nullptr;
+        return;
+    }
+
+    Node* slow = source;
+    const Node* fast = source->next;
+
+    while (fast != nullptr) {
+        fast = fast->next;
+        if (fast != nullptr) {
+            slow = slow->next;
+            fast = fast->next;
+        }
+    }
+
+    *front = source;
+    *back = slow->next;
+    slow->next = nullptr;
+}
+
+TLinkedList::Node *TLinkedList::MergeList(Node *a, Node *b)
+{
+    if (a == nullptr)
+        return b;
+    if (b == nullptr)
+        return a;
+
+    Node* result = nullptr;
+
+    if (a->person < b->person) {
+        result = a;
+        result->next = MergeList(a->next, b);
+    }
+    else {
+        result = b;
+        result->next = MergeList(a, b->next);
+    }
+    return result;
+}
+
+TLinkedList::Node *TLinkedList::MergeSort(Node *head)
+{
+    if (head == nullptr || head->next == nullptr)
+        return head;
+
+    Node* front;
+    Node* back;
+
+    MergeSortSplit(head, &front, &back);
+
+    front = MergeSort(front);
+    back = MergeSort(back);
+    return MergeList(front, back);
+
+
+}
+
+void TLinkedList::Sort()
+{
+    this->head = MergeSort(head);
+
+    Node* cur = this->head;
+    tail = nullptr;
+    while (cur) {
+        if (cur->next == nullptr)
+            tail = cur;
+        cur = cur->next;
+    }
+}
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