Interview prep, visualized
Understand the Blind 75. Don't just memorize it.
BlockStep is a visual algorithm debugger. Build each solution from blocks, then watch it run — every pointer move, every comparison, every step.
free problems work without an account · Blind 75 unlocks with a one-time pass
Two Sum (sorted)easyTWO POINTERSstep 1/15
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▲
L▲
Rleft = 0right = 5target = 10
While
Set
If
Elif
Return
▸ left < right — keep going
LeetCode tells you pass or fail. Not why.
Read a solution and it evaporates in the interview.
Patterns stick when you watch them run.
How it works
01
Build it from blocks
Assemble the algorithm from loops, conditions, and pattern blocks.
02
Step through the run
Watch pointers move, windows slide, stacks grow — one step at a time.
03
Own the pattern
The next problem with the same shape gets easier. That's the point.
Pick a problem. Watch it run.
130 problems across 18 topics. Free problems need no account; the Blind 75 set is part of the pass.
Choose a challenge
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The basics are free forever. Unlock the full Blind 75 with a pass that matches your timeline.