Hard data structure and algorithm practice puzzle.
Boxes go on a shelf in the order listed. You fill a row until the next box won't fit, then start a new row. Given the box widths and how many rows you're allowed, return the narrowest shelf width that holds every box. A shelf narrower than the widest box can't work at all.
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 Trade Bisector, a pipeline you can run and download. See every Software Engineer project.
Browse all 576 puzzles