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

Heap sort

Build a max-heap inside the array, then repeatedly move the largest value to the end and restore the heap on the rest.

Compare with

Sort [1, 2, 3, 4, 5, 6, 7]. Which value is swapped into its final place first, and why is it that value?

Step 1 of 54

root

Build a max-heap: sift down the node at index 3.

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.