leetcode-884-Uncommon-Words-from-Two-Sentences

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描述

We are given two sentences A and B. (A sentence is a string of space separated words. Each word consists only of lowercase letters.)

A word is uncommon if it appears exactly once in one of the sentences, and does not appear in the other sentence.

Return a list of all uncommon words.

You may return the list in any order.

Example 1:

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Input: A = "this apple is sweet", B = "this apple is sour"
Output: ["sweet","sour"]

Example 2:

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Input: A = "apple apple", B = "banana"
Output: ["banana"]

Note:

  1. 0 <= A.length <= 200
  2. 0 <= B.length <= 200
  3. A and B both contain only spaces and lowercase letters.

分析

用一个 Map 来存 A, B 两个数组中单词出现的次数，如果出现两次，这个单词在 A, B 两个数组都出现了，如果只出现了一次，则这个单词是题目里所要求的 uncommon word。

解决方案1(Java)

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class Solution {
    public String[] uncommonFromSentences(String A, String B) {
        Map<String, Integer> wordCountMap = new HashMap();
        for (String word: A.split(" ")) {
            wordCountMap.put(word, wordCountMap.getOrDefault(word, 0) + 1);
        }
        for (String word: B.split(" ")) {
            wordCountMap.put(word, wordCountMap.getOrDefault(word, 0) + 1);
        }
        
        List<String> result = new LinkedList();
        for (String word: wordCountMap.keySet()) {
            if (wordCountMap.get(word) == 1) {
                result.add(word);
            }
        }
        return result.toArray(new String[result.size()]);
    }
}

题目来源