[LeetCode] Problem 49 - Group Anagrams

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Given an array of strings, group anagrams together.

Example

Input: [“eat”, “tea”, “tan”, “ate”, “nat”, “bat”],

Output:

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[
  ["ate","eat","tea"],
  ["nat","tan"],
  ["bat"]
]

Note

  • All inputs will be in lowercase.
  • The order of your output does not matter.

Code

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public List<List<String>> groupAnagrams(String[] strs) {
    Map<String, List<String>> map = new HashMap<>();

    for (String str: strs) {
        int[] dic = new int[26];
        StringBuilder sb = new StringBuilder();

        for (char ch : str.toCharArray())
            dic[ch - 'a']++;

        for (int i = 0; i < dic.length; i++)
            sb.append(dic[i]);

        map.putIfAbsent(sb.toString(), new ArrayList<>());
        map.get(sb.toString()).add(str);
    }

    return new ArrayList<>(map.values());
}