LeetCode 520: Detect Capital

Meta Data

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Difficulty: easy First Attempt: 2022-08-25

• Submissions: Accepted (first try)

Approach

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Check the three valid forms directly (String Template 4): word.isupper(), word.islower(), or word[0].isupper() and word[1:].islower(). For a single character word[1:] is empty and "".islower() is False, but a single letter is already covered by the first two checks; word.istitle() is an equivalent third check for a single word.

My Solution

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class Solution:
    def detectCapitalUse(self, word: str) -> bool:
        return word.isupper() or word.islower() or word.istitle()

Complexity

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Time O(n), space O(1).

Mistakes to Avoid

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• The third form is “first uppercase and all the rest lowercase”.

Interview Explanation

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Only all caps, all lowercase or a capitalized first letter are valid, so I check isupper, islower and istitle. Time O(n).