Dice Reroll Interview Questions
Dice reroll interview question prep for threshold rules, continuation value, expected payoff, and simple optimal stopping intuition.
Candidates learning reroll, threshold, and continuation-value prompts.
Compare keep versus reroll
A reroll question asks whether the current roll is better than the value of the reroll option. The rule comes from comparing current value to continuation value.
One optional reroll
With one optional reroll of a fair die, the continuation value is 3.5. Keep rolls above 3.5 and reroll rolls below 3.5. Since rolls are integers, keep 4, 5, and 6.
Concrete expected value
The expected value with one optional reroll is the average of max(roll, 3.5) over first rolls: (3.5 + 3.5 + 3.5 + 4 + 5 + 6)/6 = 25.5/6 = 4.25.
Multiple rerolls
With more rerolls, work backward. The value with one reroll left becomes the continuation value for the earlier decision. Each extra chance changes the threshold.
Interview explanation
Explain the threshold before arithmetic. Interviewers want to see the stop-versus-continue comparison, not just a memorized expected value.
Common mistakes
Candidates often use 3.5 as the threshold even when more rerolls remain or the payoff changes. Recompute continuation value whenever rules change.
Practice the pattern
Use the LeetQuidity curriculum and calibration to turn this topic into a focused practice plan.