Longest Subsequence Repeated k Times LeetCode solution in Java

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class Solution {
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  char[] A;
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  public String longestSubsequenceRepeatedK(String s, int k) {
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    A = s.toCharArray();
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    Queue<String> queue = new ArrayDeque<>();
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    queue.offer("");
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    String ans = "";
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    int[] count = new int[26];
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    BitSet bit = new BitSet();
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    for (char ch : A)
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      if (++count[ch - 'a'] >= k) {
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        bit.set(ch - 'a');
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      }
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    while (!queue.isEmpty()) {
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      String sb = queue.poll();
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      for (int i = bit.nextSetBit(0); i >= 0; i = bit.nextSetBit(i + 1)) {
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        String res = sb + (char) (i + 'a');
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        if (check(k, res)) {
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          ans = res;
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          queue.offer(res);
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        }
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      }
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    }
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    return ans;
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  }
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  private boolean check(int k, String s) {
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    int cnt = 0;
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    for (char ch : A) {
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      if (s.charAt(cnt % s.length()) == ch && ++cnt >= k * s.length()) {
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        return true;
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      }
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    }
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    return false;
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  }
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}