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

Greedy: most non-overlapping intervals

Sort by end time and always take the interval that finishes first among those that fit. That choice never blocks a better one later.

Add an interval that ends earliest but starts earliest too. Does greedy still take the same count?

Step 1 of 18

start

Sort the intervals by end time, earliest first. The row below each end shows its start.

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.