It's basically the classic sliding window substring problem but with show titles as the elements.
Use a sliding window with a hash set to track unique show names, expanding the right pointer and shrinking the left when a duplicate is found. Keep track of the maximum window length seen. This yields O(n) time and O(min(n, m)) space, where m is the number of unique shows.
Pro tip: Clarify edge cases upfront (empty list, all unique, all same) and mention that the solution handles streaming data with a single pass. Also, discuss how you'd adapt if the list is too large to fit in memory.
Restate the problem in your own words and ask clarifying questions about input size, data types, and expected output. Confirm that 'contiguous subsequence' means a subarray of consecutive elements.
Mention that a brute force check of all subarrays would be O(n^3) or O(n^2) with a set. Then propose the sliding window with a hash set for O(n) time.
Explain the two-pointer technique: initialize left=0, max_len=0, and an empty set. Iterate right from 0 to n-1; if the show at right is in the set, remove elements from the left until it's not. Add the show at right to the set and update max_len.
State that time complexity is O(n) because each element is added and removed at most once. Space is O(min(n, m)) where m is the number of unique shows. Discuss edge cases: empty list, single element, all duplicates, and all unique.
Write clean code with meaningful variable names. Test with a few examples, including the edge cases, and trace through the logic to ensure correctness.
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