Create mergesort_linkedlist.py

Author: Alisha-786

Sorting Algorithims/mergesort_linkedlist.py

@@ -0,0 +1,77 @@
+from __future__ import annotations
+
+class Node:
+    def __init__(self, data: int) -> None:
+        self.data = data
+        self.next = None
+
+class LinkedList:
+    def __init__(self):
+        self.head = None
+
+    def insert(self, new_data: int) -> None:
+        new_node = Node(new_data)
+        new_node.next = self.head
+        self.head = new_node
+
+    def printLL(self) -> None:
+        temp = self.head
+        if temp == None:
+            return 'Linked List is empty'
+        while temp.next:
+            print(temp.data, '->', end='')
+            temp = temp.next
+        print(temp.data)
+        return
+
+# Merge two sorted linked lists
+def merge(left, right):
+    if not left:
+        return right
+    if not right:
+        return left
+
+    if left.data < right.data:
+        result = left
+        result.next = merge(left.next, right)
+    else:
+        result = right
+        result.next = merge(left, right.next)
+
+    return result
+
+# Merge sort for linked list
+def merge_sort(head):
+    if not head or not head.next:
+        return head
+
+    # Find the middle of the list
+    slow = head
+    fast = head.next
+    while fast and fast.next:
+        slow = slow.next
+        fast = fast.next.next
+
+    left = head
+    right = slow.next
+    slow.next = None
+
+    left = merge_sort(left)
+    right = merge_sort(right)
+
+    return merge(left, right)
+
+if __name__ == "__main__":
+    ll = LinkedList()
+    print("Enter the space-separated values of numbers to be inserted in the linked list prompted below:")
+    arr = list(map(int, input().split()))
+    for num in arr:
+        ll.insert(num)
+
+    print("Linked list before sorting:")
+    ll.printLL()
+
+    ll.head = merge_sort(ll.head)
+
+    print('Linked list after sorting:')
+    ll.printLL()