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3370. Smallest Number With All Set Bits 👍

  • Time: $O(\log n)$
  • Space: $O(1)$
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class Solution {
 public:
  int smallestNumber(int n) {
    return (1 << bitLength(n)) - 1;
  }

 private:
  int bitLength(int n) {
    return 32 - __builtin_clz(n);
  }
};

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class Solution {
  public int smallestNumber(int n) {
    return (1 << bitLength(n)) - 1;
  }

  private int bitLength(int n) {
    return 32 - Integer.numberOfLeadingZeros(n);
  }
}

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class Solution:
  def smallestNumber(self, n: int) -> int:
    return (1 << n.bit_length()) - 1