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

Backtracking: N-Queens

Place one queen per row. When a row has no safe column, undo the last choice and try the next. The search tries every board and keeps the valid ones.

Predict how many solutions there are for n = 3 before running it. Then check the result.

Step 1 of 80

cell being filled cells it depends on

Solve row 0 of a 4 by 4 board.

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.