From 3b3fdde97fcea3c8dcb127f97e52885da3b36e4f Mon Sep 17 00:00:00 2001
From: Tushar Nain <71440085+tm4578@users.noreply.github.com>
Date: Sat, 15 Oct 2022 22:52:28 +0530
Subject: [PATCH] Added Merge Sort for Linked List

Merge Sort to sort Linked List in efficient way using C++
---
 LinkedList/c++/MergeSort_Linked_List.cpp | 88 ++++++++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 LinkedList/c++/MergeSort_Linked_List.cpp

diff --git a/LinkedList/c++/MergeSort_Linked_List.cpp b/LinkedList/c++/MergeSort_Linked_List.cpp
new file mode 100644
index 0000000..3c53871
--- /dev/null
+++ b/LinkedList/c++/MergeSort_Linked_List.cpp
@@ -0,0 +1,88 @@
+#include <iostream>
+using namespace std;
+
+struct ListNode
+{
+    int val;
+    ListNode *next;
+    ListNode() : val(0), next(nullptr) {}
+    ListNode(int x) : val(x), next(nullptr) {}
+    ListNode(int x, ListNode *next) : val(x), next(next) {}
+};
+
+ListNode *newnode(int x, ListNode *nxt = NULL)
+{
+    ListNode *newnode = new ListNode;
+    newnode->val = x;
+    newnode->next = nxt;
+    return newnode;
+}
+
+ListNode *mergeTwoLists(ListNode *list1, ListNode *list2)
+{
+    ListNode *head = new ListNode();
+    ListNode *t = head;
+
+    ListNode *itr1 = list1, *itr2 = list2;
+
+    while (itr1 != NULL && itr2 != NULL)
+    {
+        if (itr1->val < itr2->val)
+        {
+            t->next = itr1;
+            itr1 = itr1->next;
+        }
+        else
+        {
+            t->next = itr2;
+            itr2 = itr2->next;
+        }
+
+        t = t->next;
+    }
+
+    if (itr1 != NULL)
+        t->next = itr1;
+    if (itr2 != NULL)
+        t->next = itr2;
+
+    return head->next;
+}
+
+int main()
+{
+//demo list 1
+    ListNode *t1, *t2, *t3, *t4, *t5;
+    t5 = new ListNode(9, NULL);
+    t4 = new ListNode(7, t5);
+    t3 = new ListNode(5, t4);
+    t2 = new ListNode(3, t3);
+    t1 = new ListNode(1, t2);
+    // t1->next = t2;
+    // t2->next = t3;
+    // t3->next = t4;
+    // t4->next = t5;
+    // t5->next = NULL;
+
+//demo list 2
+    ListNode *s1, *s2, *s3, *s4, *s5;
+    s5 = new ListNode(10, NULL);
+    s4 = new ListNode(8, s5);
+    s3 = new ListNode(6, s4);
+    s2 = new ListNode(4, s3);
+    s1 = new ListNode(2, s2);
+    // s1->next = s2;
+    // s2->next = s3;
+    // s3->next = s4;
+    // s4->next = s5;
+    // s5->next = NULL;
+
+    ListNode *h = mergeTwoLists(t1, s1);
+    while (h != NULL)
+    {
+        cout << h->val << " ";
+        h = h->next;
+    }
+
+    return 0;
+}