From 1051f3811c14075893a2dd2a70cc232284476290 Mon Sep 17 00:00:00 2001
From: Muskaan Rajput <106452244+muskaanrajput14@users.noreply.github.com>
Date: Thu, 6 Oct 2022 00:31:01 +0530
Subject: [PATCH] Merge Sort in Linked List in C++

---
 MergeSort_LL.cpp | 122 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 122 insertions(+)
 create mode 100644 MergeSort_LL.cpp

diff --git a/MergeSort_LL.cpp b/MergeSort_LL.cpp
new file mode 100644
index 0000000..382f457
--- /dev/null
+++ b/MergeSort_LL.cpp
@@ -0,0 +1,122 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+class Node
+{
+public:
+    int data;
+    Node *next;
+
+    Node(int data)
+    {
+        this->data = data;
+        next = NULL;
+    }
+};
+
+Node *Take_Input_2()
+{
+    int data;
+    cin >> data;
+    Node *head = NULL;
+    Node *tail = NULL;
+    while (data != -1)
+    {
+        Node *newNode = new Node(data);
+        if (head == NULL)
+        {
+            head = newNode;
+            tail = newNode;
+        }
+        else
+        {
+            tail->next = newNode;
+            tail = tail->next;
+        }
+        cin >> data;
+    }
+    return head;
+}
+
+void print(Node *head)
+{
+    Node *temp = head;
+    while (temp != NULL)
+    {
+        cout << temp->data << " -> ";
+        temp = temp->next;
+    }
+
+    if (temp == NULL)
+    {
+        cout << "NULL";
+    }
+}
+
+Node *mergeTwoSortedLL(Node *head1, Node *head2)
+{
+    if (head1 == NULL)
+    {
+        return head2;
+    }
+
+    if (head2 == NULL)
+    {
+        return head1;
+    }
+
+    Node *temp1 = head1;
+    Node *temp2 = head2;
+    Node *finalTail = NULL;
+    Node *finalHead = NULL;
+
+    if (temp1->data <= temp2->data)
+    {
+        finalHead = temp1;
+        finalTail = temp1;
+        temp1 = temp1->next;
+    }
+    else
+    {
+        finalHead = temp2;
+        finalTail = temp2;
+        temp2 = temp2->next;
+    }
+
+    while (temp1 != NULL && temp2 != NULL)
+    {
+        if (temp1 -> data <= temp2 -> data)
+        {
+            finalTail -> next = temp1;
+            finalTail = finalTail -> next;
+            temp1 = temp1->next;
+        }
+        else
+        {
+            finalTail -> next = temp2;
+            finalTail = finalTail -> next;
+            temp2 = temp2 -> next;
+        }
+    }
+
+    if(temp1 == NULL)
+    {
+        finalTail -> next = temp2;
+    }
+
+    if(temp2 == NULL)
+    {
+        finalTail -> next = temp1;
+    }
+    return finalHead;
+}
+
+int main()
+{
+    Node *head1 = Take_Input_2();
+    Node *head2 = Take_Input_2();
+    //print(head);
+    Node* head3 = mergeTwoSortedLL(head1, head2);
+    print(head3);
+    return 0;
+}