Linked Structures

Traverse and Print

Walk from the head pointer to null, visiting each node exactly once without random indexing.

Algorithm

The replay labels nodes by value, such as node(20), and never exposes object identity or memory addresses. This Dart DSA implementation uses the same small chain as the rest of the DSA track.

cursor A cursor reference names the node currently being visited.
null stop Traversal ends when the cursor reaches the null marker.

Basic Implementation

basic.dart
Replay: real traced execution (multi-file project)
class Node {
  int value;
  Node? next;
  Node(this.value, [this.next]);
}

String render(Node? head) {
  final parts = <String>[];
  var cursor = head;
  while (cursor != null) {
    parts.add(cursor.value.toString());
    cursor = cursor.next;
  }
  return '${parts.join(' -> ')} -> null';
}

void main() {
  var head = Node(10, Node(20, Node(30)));
  print(render(head));
}

  1. head ← 10 -> 20 -> 30 -> null

    1class Node {2  int value;
    values this step10 -> 20 -> 30 -> nullhead

  2. output ← 10

    9var cursor = head;10while (cursor != null) {11  parts.add(cursor.value.toString());
    values this step10outputnode(10)cursor

  3. output ← 10 -> 20

    9var cursor = head;10while (cursor != null) {11  parts.add(cursor.value.toString());
    values this step10 -> 20outputnode(20)cursor

  4. output ← 10 -> 20 -> 30 -> null

    9var cursor = head;10while (cursor != null) {11  parts.add(cursor.value.toString());
    values this step10 -> 20 -> 30 -> nulloutputnode(30)cursor

  5. stdout ← 10 -> 20 -> 30 -> null

    18  var head = Node(10, Node(20, Node(30)));19  print(render(head));20}
    values this step10 -> 20 -> 30 -> nullstdout10 -> 20 -> 30 -> nulloutput

Complexity

  • Time: O(n)
  • Space: O(1)

Implementation notes

  • Keep the explicit node and pointer/reference operations; array shortcuts hide the linked-list state this lesson is meant to replay.
  • The final output prints the chain in a deterministic a -> b -> null form for cross-language comparison.