Linked List - LeetCode

LinkedL.py

   # cycle in a inked lists
    def hasCycle(self, head: ListNode) -> bool:
        first = head
        second = head
        while first and second and second.next: # Important takes care of edge cases
            first = first.next
            second = second.next.next
            if first == second:
                return True
        return False
    
    #  intersection of two singly linked lists
     def getIntersectionNode(self, headA, headB):
        curA,curB = headA,headB
        lenA,lenB = 0,0
        while curA is not None:
            lenA += 1
            curA = curA.next
        while curB is not None:
            lenB += 1
            curB = curB.next
        curA,curB = headA,headB # reassign value
        if lenA > lenB:
            for i in range(lenA-lenB):
                curA = curA.next
        elif lenB > lenA:
            for i in range(lenB-lenA):
                curB = curB.next
        while curB != curA:
            curB = curB.next
            curA = curA.next
        return curA
   
   # Delete Duplicate nodes in a Linked List
    def deleteDuplicates(self, head: ListNode) -> ListNode:
        cur = head
        while cur and cur.next:
            if cur.val == cur.next.val:
                cur.next = cur.next.next # setting duplicate node value equal to new one
            else:
                cur = cur.next
        return head
    
    # Palindrome
   def isPalindrome(head):
    cur, fast, slow = head
    
    # Get the midoint using slow
    while fast and fast.next:
        fast = fast.next.next
        slow = slow.next
    stack = [slow.val]
    # Push the second half into the stack
    while slow:
        slow = slow.next
        stack.append(slow.val)
    # Compare
    while stack:
        if stack.pop == cur.val:
            cur = cur.next
        else:
            return False
    return True