DSA · Theory

Sort a linked list of 0s, 1s and 2s

Theory

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Sort a linked list of 0s, 1s and 2s

Sort a linked list of 0s, 1s and 2s sits in a counter. Neha’s job is a ticket queue node. Write that first.

Keep Sort a linked list of 0s, 1s and 2s small. Neha should finish a ticket queue node in a few lines, not a 40-line dump.

Sort a linked list of 0s, 1s and 2s exists so Neha can keep a ticket queue node correct in a counter.

Sort a linked list of 0s, 1s and 2s shows up in a counter. Name a ticket queue node, not “a real-world scenario”.

Sort a linked list of 0s, 1s and 2s trap: losing the next pointer on delete. Neha loses marks for that every viva.

After Sort a linked list of 0s, 1s and 2s, Neha should still remember losing the next pointer on delete.

One breath for Sort a linked list of 0s, 1s and 2s, then a ticket queue node, then losing the next pointer on delete. Sit down.

Diagram

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

Exam tip

Board: a ticket queue node. Dry-run Sort a linked list of 0s, 1s and 2s. Name the trap: 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

Sort a linked list of 0s, 1s and 2s — a linked list chains nodes with next pointers instead of contiguous indexes.

Short notes

DefSort a linked list of 0s, 1s and 2s — Neha uses it for a ticket queue node in a counter.
RuleSort a linked list of 0s, 1s and 2s → head → next → ….
RememberSort a linked list of 0s, 1s and 2s + a dry-run table (a counter).
UseSort a linked list of 0s, 1s and 2s in a counter (a ticket queue node).
TrapSort a linked list of 0s, 1s and 2s — losing the next pointer on delete.
ExSort a linked list of 0s, 1s and 2s → 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

Sort a linked list of 0s, 1s and 2s

Example

Short notes

Questions

Sort a linked list of 0s, 1s and 2s

Example

Short notes

Questions