Maximum Length of a Concatenated String with Unique Characters LeetCode solution in Java

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class Solution {
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  public int maxLength(List<String> arr) {
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    String[] words =
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        arr.stream().filter(o -> o.chars().distinct().count() == o.length()).toArray(String[]::new);
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    int[] dp = new int[1 << words.length];
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    int[] ok = new int[1 << words.length];
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    for (int i = 0; i < words.length; i++) {
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      for (char ch : words[i].toCharArray()) {
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        ok[1 << i] |= 1 << (ch - 'a');
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        dp[1 << i]++;
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      }
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    }
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    int ans = 0;
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    for (int i = 0; i < dp.length; i++) {
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      if ((ok[i & (i - 1)] & ok[i & -i]) == 0) {
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        dp[i] = dp[i & (i - 1)] + dp[i & -i];
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        ok[i] = ok[i & (i - 1)] | ok[i & -i];
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      }
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      ans = Math.max(ans, dp[i]);
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    }
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    return ans;
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  }
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}