Check Alternating Highs and Lows Around a Circular Array

An array is connected end to end to form a circle. Determine whether its values strictly alternate between a high point and a low point around the entire circle. Implement `is_alternating_circle(values: int[]) -> bool`. Every element must be strictly greater than both of its neighbors or strictly less than both of its neighbors. The first and last elements are neighbors. ### Constraints & Assumptions - There are between 2 and 200,000 elements, each between -1,000,000,000 and 1,000,000,000. - Equal neighboring values are not allowed in a valid alternating circle. - For length two, both neighbor positions of an element refer to the other element. Two distinct values therefore form a valid alternating circle. - Strict comparisons and the length-two convention are explicit practice choices for the reported high/low pattern. - Return one Boolean; no rotation or rearrangement of the input is allowed. ### Examples - `[1, 4, 2, 5]` returns `true`. Each low value has two higher neighbors and each high value has two lower neighbors, including across the last-to-first boundary. - `[1, 4, 2]` returns `false`. The value 2 is lower than 4 but higher than 1, so it is neither a high nor a low point. ```hint Include the closing edge A linearly alternating prefix does not prove the circle works. Check each value against both neighbors using wraparound indices. ```