DSA · Theory

Flattening a Linked List

Theory

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Flattening a Linked List

If you can teach Flattening a Linked List using a ticket queue node, you know it. If you only know the heading, you don’t.

Keep Flattening a Linked List small. Amit should finish a ticket queue node in a few lines, not a 40-line dump.

Flattening a Linked List exists so Amit can keep a ticket queue node correct in a counter.

Use Flattening a Linked List when a ticket queue node must stay clear. If a simpler DSA step works, use that instead.

Flattening a Linked List miss — losing the next pointer on delete. Fix it before you talk about advanced DSA.

After Flattening a Linked List, Amit should still remember losing the next pointer on delete.

Close Flattening a Linked List with: “If I skip it, a ticket queue node goes wrong like this: losing the next pointer on delete.”

Diagram

  [10] → [20] → [30] → /
   head              tail

Exam tip

Say Flattening a Linked List in one breath, then head → next → …, then losing the next pointer on delete.

Example

class Node:
    def __init__(self, val, next=None):
        self.val = val
        self.next = next

head = Node(1, Node(2, Node(3)))
cur = head
while cur:
    print(cur.val, end=" -> " if cur.next else "\n")
    cur = cur.next

Flattening a Linked List — a linked list chains nodes with next pointers instead of contiguous indexes.

Short notes

DefFlattening a Linked List — Amit uses it for a ticket queue node in a counter.
RuleFlattening a Linked List → head → next → ….
RememberFlattening a Linked List + time vs memory (a counter).
UseFlattening a Linked List in a counter (a ticket queue node).
TrapFlattening a Linked List — losing the next pointer on delete.
ExFlattening a Linked List → a ticket queue node.

class Node: def __init__(self, val, next=None): self.val = val self.next = next head = Node(1, Node(2, Node(3))) cur = head while cur: print(cur.val, end=" -> " if cur.next else "\n") cur = cur.next

Flattening a Linked List

Example

Short notes

Questions

Flattening a Linked List

Example

Short notes

Questions