sorting linked list

Author: raianmol172

merge_sort_linked_list.py

@@ -0,0 +1,86 @@
+class Node:
+    def __init__(self, data):
+        self.data = data
+        self.next = None
+
+
+class LinkedList:
+    def __init__(self):
+        self.head = None
+
+    def append(self, data):
+        if not self.head:
+            self.head = Node(data)
+            return
+        new_node = Node(data)
+        curr = self.head
+        while curr.next:
+            curr = curr.next
+        curr.next = new_node
+        return
+
+    def sortedMerge(self, a, b):
+        result = None
+
+        if a == None:
+            return b
+        if b == None:
+            return a
+
+        if a.data <= b.data:
+            result = a
+            result.next = self.sortedMerge(a.next, b)
+        else:
+            result = b
+            result.next = self.sortedMerge(a, b.next)
+        return result
+
+
+    def mergeSort(self, head):
+
+        if head == None or head.next == None:
+            return head
+
+        middle = self.getMiddle(head)
+        nexttomiddle  = middle.next
+        middle.next = None
+
+        left = self.mergeSort(head)
+        right = self.mergeSort(nexttomiddle)
+
+        sortedlist = self.sortedMerge(left, right)
+        return sortedlist
+
+    def getMiddle(self, head):
+
+        if head == None:
+            return head
+
+        slow = head
+        fast = head
+
+        while slow.next != None and slow.next.next != None:
+
+            slow = slow.next
+            fast = fast.next.next
+
+        return slow
+
+
+    def printList(self):
+        temp = self.head
+        while temp:
+            print(temp.data, end= " ")
+            temp = temp.next
+        print(' \n ')
+
+
+l1 = LinkedList()
+l1.append(40)
+l1.append(30)
+l1.append(20)
+l1.append(10)
+l1.printList()
+l1.head = l1.mergeSort(l1.head)
+print("after sorting linked list:")
+l1.printList()