Contains Duplicate

Write `has_duplicate(nums)` that returns `True` when any value appears more than once in the list, and `False` when every value is distinct. has_duplicate([1, 2, 3, 1]) -> True has_duplicate([1, 2, 3, 4]) -> False Sorting first works and costs O(n log n). The point of this one is the trade you make instead: spend memory to buy time, and return the moment you have your answer rather than finishing the scan.