Linked List Comparison

Comparing Two Linked Lists

Comparing two linked lists involves checking whether both lists contain the same sequence of values in the same order.

This is typically done using a pointer approach where we traverse both lists simultaneously and compare values at each corresponding node.

Tip: Merging is efficient when input lists are already sorted and doesn’t require extra space beyond a few pointers.

Steps to Compare

  1. Start from the head node of both linked lists
  2. Iterate through both lists simultaneously
  3. At each step, compare the values of the current nodes
  4. If values differ or one list ends before the other, the lists are not the same
  5. If both lists end together without mismatches, they are considered equal

Edge Cases

  • Both lists are empty
  • One list is empty
  • Lists have different lengths
  • Lists have same length but different values
  • Lists are exactly the same

Best Practices

  • Ensure both lists are of similar structure before comparing
  • Traverse both lists node by node to avoid missing mismatches
  • Use dummy data to test all edge cases including empty and unequal lists
  • If lists contain objects, consider deep comparison of values
  • Track index or pointer position for debugging mismatches

Visualize comparison of two linked lists node by node

List 1
List 2
Pointer

List 1

Generate List 1 to begin

List 2

Generate List 2 to continue

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Comparing Quiz Challenge

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Linked List Comparison Implementation

class Node {
  constructor(data) {
    this.data = data;
    this.next = null;
  }
}

function compareLists(l1, l2) {
  while (l1 && l2) {
    if (l1.data !== l2.data) return false;
    l1 = l1.next;
    l2 = l2.next;
  }
  return l1 === null && l2 === null;
}

Explore Other Operations

Insertion

Deletion

Traversal

Merging

Searching

Reverse