0049-group-anagrams.java

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

        for (String s : strs) {
            int[] count = new int[26];

            for (char c : s.toCharArray()) {
                count[c - 'a']++;
            }

            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < 26; i++) {
                sb.append('#');
                sb.append(count[i]);
            }
            String key = sb.toString();
            
            if (!res.containsKey(key)) {
                res.put(key, new ArrayList<>());
            }
            res.get(key).add(s);
        }

        return new ArrayList<>(res.values());
    }
}
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class Solution {
    public List<List<String>> groupAnagrams(String[] strs) {
        Map<String, List<String>> map = new HashMap<>();
        
        for (String word : strs) {
            char[] chars = word.toCharArray();
            Arrays.sort(chars);
            String sortedWord = new String(chars);
            
            if (!map.containsKey(sortedWord)) {
                map.put(sortedWord, new ArrayList<>());
            }
            
            map.get(sortedWord).add(word);
        }
        
        return new ArrayList<>(map.values());
    }
}