Medium data structure and algorithm practice puzzle.
Given two strings where "#" means backspace, return true if they end up as the same text. Type each one out with a stack: push normal letters, and pop on "#". A backspace on empty text does nothing. Then compare the two results.
Solve it three ways: snap the jigsaw pieces together, fill in the blanks, or type it from scratch against the tests. This one is free.
Every line of the solution comes with a note explaining why it is there, and a step by step replay shows the code running. At level 3, where you type it yourself, you can ask for an AI mock interview on this problem that ends with a hiring manager's scorecard.
Then grow it into a real project with the Software Engineer button: this puzzle becomes the Document Expression Evaluator, a pipeline you can run and download. See every Software Engineer project.
Browse all 576 puzzles