884. Uncommon Words from Two Sentences

Problem

A sentence is a string of single-space separated words where 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.

Given two sentences s1 and s2, return **a list of all the *uncommon words***. You may return the answer in *any order*.

  Example 1:

Input: s1 = "this apple is sweet", s2 = "this apple is sour"
Output: ["sweet","sour"]

Example 2:

Input: s1 = "apple apple", s2 = "banana"
Output: ["banana"]

Constraints:

• 1 <= s1.length, s2.length <= 200

• s1 and s2 consist of lowercase English letters and spaces.

• s1 and s2 do not have leading or trailing spaces.

• All the words in s1 and s2 are separated by a single space.

Solution (Java)

class Solution {
    public String[] uncommonFromSentences(String s1, String s2) {
        Map<String, Integer> map = new HashMap<>();
        for (String word : s1.split(" ")) {
            map.put(word, map.getOrDefault(word, 0) + 1);
        }
        for (String word : s2.split(" ")) {
            map.put(word, map.getOrDefault(word, 0) + 1);
        }
        List<String> result = new ArrayList<>();
        for (Map.Entry<String, Integer> entry : map.entrySet()) {
            if (entry.getValue() == 1) {
                result.add(entry.getKey());
            }
        }
        String[] strs = new String[result.size()];
        result.toArray(strs);
        return strs;
    }
}

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).