Last Stone Weight II

MediumDynamic Programming1d dp

Solve this the way you would in the interview: out loud, on a timer, with an AI interviewer asking follow-ups while you code. You get a scored report at the end.

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Problem

You have stones with positive integer weights stones[i]. In each turn you pick any two stones with weights x <= y and smash them: if x == y both are destroyed, otherwise the lighter one is destroyed and the heavier one's weight becomes y - x. You keep going until at most one stone remains. Return the smallest possible weight of the final stone, or 0 if no stones are left.

Examples

Input: stones = [2,7,4,1,8,1]
Output: 1
One smashing order leaves a single stone of weight 1; nothing better is possible.
Input: stones = [31,26,33,21,40]
Output: 5
Split into {26, 21, 31} = 78 and {33, 40} = 73; the difference 5 is the smallest achievable.

Constraints

  • 1 <= stones.length <= 30
  • 1 <= stones[i] <= 100

What the interviewer grades

A correct solution is one of five scores. The report also grades problem understanding (did you clarify inputs and edge cases before coding), problem solving, communication while you work, code quality, and testing. See a sample report, or read up on the pattern in the lessons.

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