Hard data structure and algorithm practice puzzle.
Given an image and a smaller kernel, both as 2D grids, slide the kernel over every spot where it fully fits and return the grid of weighted sums, rounded to 3 decimals. At each spot, multiply the overlapping values and add them up. The output shrinks by the kernel size minus 1 in each direction. Every edge detector in a vision model is one of these kernels.
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 Sample Region Mapper, a pipeline you can run and download. See every Software Engineer project.
Browse all 576 puzzles