Maximum Number of Removable Characters LeetCode solution in Java

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class Solution {
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  public int maximumRemovals(String s, String p, int[] removable) {
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    int left = 0, right = removable.length;
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    while (left < right) {
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      int middle = (right + left + 1) / 2;
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      String afterRemoval = remove(s, removable, middle);
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      if (isSubsequence(p, afterRemoval, p.length(), afterRemoval.length())) left = middle;
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      else right = middle - 1;
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    }
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    return left;
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  }
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  private String remove(String s, int[] removable, int k) {
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    char[] symbols = s.toCharArray();
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    for (int i = 0; i < k; i++) {
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      symbols[removable[i]] = Character.MIN_VALUE;
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    }
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    return String.valueOf(symbols);
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  }
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  private boolean isSubsequence(
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      String subSequence, String word, int subSequenceChar, int wordChar) {
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    if (subSequenceChar == 0) return true;
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    if (wordChar == 0) return false;
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    if (subSequence.charAt(subSequenceChar - 1) == word.charAt(wordChar - 1))
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      return isSubsequence(subSequence, word, subSequenceChar - 1, wordChar - 1);
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    return isSubsequence(subSequence, word, subSequenceChar, wordChar - 1);
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  }
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}