DSA · Theory

Josephus circle using circular linked list

Theory

709/810

Josephus circle using circular linked list

If you can teach Josephus circle using circular linked list using a ticket queue node, you know it. If you only know the heading, you don’t.

Keep Josephus circle using circular linked list small. Sara should finish a ticket queue node in a few lines, not a 40-line dump.

Josephus circle using circular linked list exists so Sara can keep a ticket queue node correct in a counter.

Use Josephus circle using circular linked list when a ticket queue node must stay clear. If a simpler DSA step works, use that instead.

Josephus circle using circular linked list trap: losing the next pointer on delete. Sara loses marks for that every viva.

After Josephus circle using circular linked list, Sara should still remember losing the next pointer on delete.

Close Josephus circle using circular 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

For Josephus circle using circular linked list: definition + a counter + one failure.

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

Josephus circle using circular linked list — a linked list chains nodes with next pointers instead of contiguous indexes.

Short notes

DefJosephus circle using circular linked list — Sara uses it for a ticket queue node in a counter.
RuleJosephus circle using circular linked list → head → next → ….
RememberJosephus circle using circular linked list + time vs memory (a counter).
UseJosephus circle using circular linked list in a counter (a ticket queue node).
TrapJosephus circle using circular linked list — losing the next pointer on delete.
ExJosephus circle using circular 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

Josephus circle using circular linked list

Example

Short notes

Questions

Josephus circle using circular linked list

Example

Short notes

Questions