Circular Permutation in Binary Representation LeetCode solution in Java

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class Solution {
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  public List<Integer> circularPermutation(int n, int start) {
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    List<Integer> l = new ArrayList<Integer>();
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    int i = 0;
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    int len = (int) Math.pow(2, n);
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    int[] arr = new int[len];
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    while (i < len) {
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      arr[i] = (i) ^ (i / 2);
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      i++;
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    }
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    i = 0;
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    while (arr[i] != start) i++;
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    while (i < arr.length) {
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      l.add(arr[i]);
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      i++;
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    }
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    i = 0;
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    while (i < arr.length && arr[i] != start) {
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      l.add(arr[i]);
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      i++;
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    }
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    return l;
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  }
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}