K-th Symbol in Grammar LeetCode solution in Java

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class Solution {
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  public int kthGrammar(int n, int k) {
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    if (n == 1 || k == 1) {
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      return 0;
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    }
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    int length = (int) Math.pow(2, n - 1);
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    int mid = length / 2;
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    if (k <= mid) {
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      return kthGrammar(n - 1, k);
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    } else if (k > mid + 1) {
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      return invert(kthGrammar(n - 1, k - mid));
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    } else {
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      return 1;
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    }
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  }
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  static int invert(int x) {
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    if (x == 0) {
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      return 1;
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    }
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    return 0;
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  }
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}