LeetCode 884: Uncommon Words from Two Sentences

Meta Data

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Difficulty: easy First Attempt: 2022-09-21

• Submissions: Wrong Answer → Accepted ×2

Approach

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“Exactly once in one sentence and absent from the other” equals “exactly once across both”. Join, split(), count, and keep words with count 1 (Hash Table Template 1).

My Attempts

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Attempt 1 forgot to split and looped over the string, counting characters: "b", "b" returned the separating space [" "].

Solution

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class Solution:
    def uncommonFromSentences(self, s1: str, s2: str) -> List[str]:
        cnt = Counter((s1 + " " + s2).split())
        return [w for w, c in cnt.items() if c == 1]

Complexity

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Time O(n + m), space O(n + m).

Mistakes to Avoid

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• split() into words first; iterating a string yields characters.

Interview Explanation

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I join both sentences, split into words, count, and return the words seen exactly once. Time O(n + m).