Formatted question description: https://leetcode.ca/all/884.html

884. Uncommon Words from Two Sentences (Easy)

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:

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

Example 2:

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.

Related Topics:
Hash Table

Solution 1.

// OJ: https://leetcode.com/problems/uncommon-words-from-two-sentences/

// Time: O(A+B)
// Space: O(A+B)
class Solution {
private:
    unordered_map<string, int> getCounts(string s) {
        istringstream ss(s);
        string word;
        unordered_map<string, int> m;
        while (ss >> word) m[word]++;
        return m;
    }
public:
    vector<string> uncommonFromSentences(string A, string B) {
        auto m = getCounts(A), n = getCounts(B);
        vector<string> ans;
        for (auto &p : m) {
            if (p.second == 1 && n.find(p.first) == n.end()) ans.push_back(p.first);
        }
        for (auto &p : n) {
            if (p.second == 1 && m.find(p.first) == m.end()) ans.push_back(p.first);
        }
        return ans;
    }
};

Java

class Solution {
    public String[] uncommonFromSentences(String A, String B) {
        List<String> uncommonWords = new ArrayList<String>();
        Set<String> set = new HashSet<String>();
        String[] strA = A.split(" ");
        String[] strB = B.split(" ");
        for (String word : strA) {
            if (set.add(word))
                uncommonWords.add(word);
            else
                uncommonWords.remove(word);
        }
        for (String word : strB) {
            if (set.add(word))
                uncommonWords.add(word);
            else
                uncommonWords.remove(word);
        }
        int length = uncommonWords.size();
        String[] uncommonWordsArray = new String[length];
        for (int i = 0; i < length; i++)
            uncommonWordsArray[i] = uncommonWords.get(i);
        return uncommonWordsArray;
    }
}

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