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

Merge sort

Split the array in half, sort each half, then merge two sorted halves by repeatedly taking the smaller front value.

Compare with

Pick an array of 5 values. How many levels of splitting happen before every half has one value?

Step 1 of 40

Split a[0..7] at mid = 3. Sort each half first.

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.