Check if the number is odd ?

Solution #1. Check if num % 2 == 0
boolean isOdd = (num % 2 == 1);

Problem. It will not return correct result for -ve number


Solution #2. Same approach but use absolute value of num
if(num<0) {
   num = -(num);
}
boolean isOdd = (num % 2 == 1);

Solution #3. Check using bitwise & with 1 (Binary = 000000...1)

boolean isOdd = (num & 1) != 0;

Example

21 = 10101

  1 = 00001

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        00001  => Odd, Yes.

Fastest and most optimized solution.