Medium data structure and algorithm practice puzzle.
Given two qubits as [control, target], apply a CNOT gate and return the new [control, target]. If the control is 1, flip the target. If it's 0, leave both alone. The control never changes. CNOT is the gate that creates entanglement.
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 Shot Intake Pipeline, a pipeline you can run and download. See every Software Engineer project.
Browse all 576 puzzles