complement_of_base10.md

1009. Complement of Base 10 Integer

• idea is to take all the bits and XOR them.
• we were unaware of the size, so we did find that out first.
• there are more optimal approach, will add them.

implementation

int bitwiseComplement(int n) {
  if (n == 0) return 1;
  int temp = n;
  int Size = 0;
  while (temp) {
    temp = temp >> 1;
    Size ++;
  }

  for (int i = 0; i < Size; i++)
    n ^= (1 << i);

  return n;
}

more concise

int bitwiseComplement(int n) {
    if (n == 0) return 1;

    for (int temp = n, i = 0; (temp > 0); temp = temp >> 1, i++)
        n ^= (1 << i);

    return n;
}