[leetcode] problem 49 – group anagrams

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());
}