Algorithm visualizer

See every step, with your own input

Pick an algorithm, enter your own numbers or use a preset, then step through the run. The pseudocode and the explanation follow each step.

Arrays and searching

Sorting

Stacks, queues and Fenwick tree

Trees and tries

Graphs

Dynamic programming

Greedy and backtracking

Breadth-first search (BFS)

Explore outward in rings: visit every neighbour of the start, then their neighbours, and so on. A queue drives the order.

Start from node 0 in the connected preset. Which nodes are at distance 2, and in what order does BFS find them?

Step 1 of 37

Queue (front on the left)0

Start at 0. Mark it seen and put it in the queue.

Speed

Labels under values name their role, such as lo, hi, mid, i, j, min, L and R. Faded items are already ruled out or already in place.

Breadth-first search (BFS)

Explore outward in rings: visit every neighbour of the start, then their neighbours, and so on. A queue drives the order.