Naming a Company LeetCode solution in Java

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class Solution {
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  public long distinctNames(String[] ideas) {
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    // HashSet + String Manipulation; TC: O(26*26*n); SC: O(26*n)
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    HashSet<String>[] arr = new HashSet[26];
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    for (int i = 0; i < 26; i++) {
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      arr[i] = new HashSet<>();
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    }
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    for (String s : ideas) {
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      arr[s.charAt(0) - 'a'].add(s.substring(1));
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    }
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    long ans = 0, cnt;
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    for (int i = 0; i < 26; i++) {
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      for (int j = i + 1; j < 26; j++) {
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        cnt = 0;
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        for (String str : arr[j]) {
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          if (arr[i].contains(str)) cnt++;
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        }
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        ans += 2 * (arr[i].size() - cnt) * (arr[j].size() - cnt);
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      }
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    }
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    return ans;
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  }
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}