Quant interview recall
Brainteasers
Forty original puzzle families practice invariants, counting, expectation and decisions. State your assumptions, try a solution, then reveal the reasoning and a transfer question.
A routine for solving an unfamiliar interview puzzle
- Restate the question. Identify what is fixed, what is random, what you control and which quantity is requested.
- Try a small case or draw the possible states. Look for an invariant, symmetry, counting argument or recurrence before calculating.
- State the assumptions that make your method work. For a strategy, supply a construction as well as a bound.
- Check an extreme case and explain the answer aloud. A correct number with an unsupported method still needs work.
Use the scratchpad to record these steps. The displayed result measures answer correctness and recorded help use; it does not grade your proof or interview delivery.