Easy data structure and algorithm practice puzzle.
Given the raw bits of a signed integer, read as an unsigned number, and its width in bits, return the value it actually stores. In two's complement the top bit is worth minus 2 to the power width - 1 instead of plus, which is why the byte 11111111 means -1 and not 255, and why one adder circuit can add signed and unsigned numbers without knowing which it is doing.
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.
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