Python Program For Sorting Linked List Which Is Already Sorted On Absolute Values

# Python3 program to sort a linked list, 
# already sorted by absolute values 
    
# Linked list Node
class Node:
    def __init__(self, d):
        self.data = d 
        self.next = None

class SortList:
    def __init__(self):
        self.head = None
        
    # To sort a linked list by actual values. 
    # The list is assumed to be sorted by 
    # absolute values. 
    def sortedList(self, head):
        
        # Initialize previous and 
        # current nodes 
        prev = self.head 
        curr = self.head.next
        
        # Traverse list 
        while(curr != None): 
            
            # If curr is smaller than prev, 
            # then it must be moved to head 
            if(curr.data < prev.data):
                
                # Detach curr from linked list 
                prev.next = curr.next
                
                # Move current node to beginning 
                curr.next = self.head 
                self.head = curr
                
                # Update current 
                curr = prev 
            
            # Nothing to do if current element 
            # is at right place 
            else:
                prev = curr
        
            # Move current 
            curr = curr.next
        return self.head 
    
    # Inserts a new Node at front of 
    # the list
    def push(self, new_data):
        
        # 1 & 2: Allocate the Node & 
        #        Put in the data
        new_node = Node(new_data) 
    
        # 3. Make next of new Node as head 
        new_node.next = self.head 
    
        # 4. Move the head to point to 
        # new Node 
        self.head = new_node
    
    # Function to print linked list 
    def printList(self, head):
        temp = head
        while (temp != None): 
            print(temp.data, end = " ")
            temp = temp.next
        print() 
    
# Driver Code
llist = SortList()

# Constructed Linked List is  
# 1->2->3->4->5->6->7->8->8->9->null 
llist.push(-5) 
llist.push(5) 
llist.push(4) 
llist.push(3) 
llist.push(-2) 
llist.push(1) 
llist.push(0) 
        
print("Original List :") 
llist.printList(llist.head)
        
start = llist.sortedList(llist.head)

print("Sorted list :") 
llist.printList(start)

# This code is contributed by Prerna Saini