A strictly increasing linked list in Python

Suppose we have head of a singly linked list, we have to check whether the values of the nodes are sorted in a strictly ascending order or not.

So, if the input is like [2,61,105,157], then the output will be True.

To solve this, we will follow these steps −

• Define a function solve() . This will take head

• if head.next is null, then

  • return True

• if head.val >= head.next.val, then

  • return False

• return solve(head.next)

Let us see the following implementation to get better understanding −

Example

 Live Demo

class ListNode:
   def __init__(self, data, next = None):
      self.val = data
      self.next = next
def make_list(elements):
   head = ListNode(elements[0])
   for element in elements[1:]:
      ptr = head
      while ptr.next:
         ptr = ptr.next
      ptr.next = ListNode(element)
   return head
class Solution:
   def solve(self, head):
      if head.next == None:
         return True
      if head.val >= head.next.val:
         return False
      return self.solve(head.next)
ob = Solution()
head = make_list([2,61,105,157])
print(ob.solve(head))

Input

[2,61,105,157]

Output

True