Given an array of unique numbers, return any element that is smaller than its neighbors. Then discuss the two-dimensional follow-up where you need to find a cell smaller than its adjacent neighbors. ### Constraints & Assumptions - For the 1D problem, neighbors are immediate left and right elements. - Boundary elements have only one neighbor unless clarified. - Array elements are unique. - For 2D, adjacency means up, down, left, and right. ### Clarifying Questions to Ask - Can boundary elements be local minima? - What should be returned: value or index? - Are all values unique in 2D? - Is O(log n) expected for 1D? - What constraints apply to the matrix? ### What a Strong Answer Covers ```premium-lock What a Strong Answer Covers ``` ### Follow-up Questions - How would duplicates change the solution? - How would you return all local minima? - Can 2D be solved with divide and conquer? - What if diagonal neighbors count too?