Given a lowercase English string s, return the number of contiguous substrings that
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consist only of vowels from the set {a, e, i, o, u}, and
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contain each of the five vowels at least once. Constraints: 1 <= |s| <= 200000. Design an O(n) time solution using a sliding-window/two-pointer approach with O(
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extra space. Explain how you handle consonants that break windows, repeated vowels, and long runs of vowels. Provide code and analyze time and space complexity.