You are given a sorted list of distinct integers from 0 to 99, for instance [0, 1, 2, 50, 52, 75].
Your task is to produce a string that describes the numbers missing from the list; in this case "3,49,51,53-74,76-99".
This problem asks you to scan a sorted list of distinct integers in the range 0 to 99 and return a compact string describing all missing values. The key idea is to compare neighboring numbers, emit single missing numbers directly, and merge longer gaps into ranges such as 53-74. You also need to handle missing numbers before the first element and after the last element. A simple linear pass is enough, making the solution straightforward and efficient.
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