Linked Lists —
Pointers made visible.
Linked list bugs almost always come from wrong pointer assignments. When your code says node.next = new_node, what actually happens? Where does the arrow go? LearnBug shows every pointer as a live arrow — watch nodes link and unlink, and see exactly where your pointer logic breaks.
What is a Linked List?
A linked list is a sequence of nodes, where each node holds a value and a pointer to the next node. Unlike arrays, linked lists don't require contiguous memory — they can grow and shrink dynamically. They're used in stacks, queues, symbol tables, and even in how your browser manages history.
Why visualization helps
The hardest part of linked lists is understanding pointers. LearnBug makes every pointer visible — you see nodes as boxes connected by arrows, and every operation animates in real time. Reversal, deletion, cycle detection — all made obvious once you see the arrows move.
Every linked list operation, animated
Reverse a Linked List
The most asked linked list interview question. Watch three pointers — prev, curr, next — reassign arrows until the entire list points backward.
Detect Cycle (Floyd's)
Fast and slow pointer — the hare and tortoise algorithm. Watch both pointers traverse the list and see the inevitable moment they meet if a cycle exists.
Merge Two Sorted Lists
Pointer-by-pointer merge. Watch two lists interleave their nodes in sorted order — the building block of merge sort on linked lists.
Find the Middle Node
Fast and slow pointer again — but this time to find the midpoint. Watch slow advance one step while fast advances two, and meet in the middle.
Remove Nth Node from End
Two-pass vs one-pass. Watch the two-pointer approach maintain a fixed gap — and the target node's predecessor close the gap on arrival.
Run your linked list code on LearnBug
Watch every pointer assignment update the live node diagram — catch wrong links instantly.