Find whether a given number is a power of 4 or not | GeeksforGeeks
3. A number n is a power of 4 if following conditions are met.
a) There is only one bit set in the binary representation of n (or n is a power of 2)
b) The count of zero bits before the (only) set bit is even.
Another solution is to keep dividing the number by 4, i.e, do n = n/4 iteratively. In any iteration, if n%4 becomes non-zero and n is not 1 then n is not a power of 4, otherwise n is a power of 4.
http://sidbai.github.io/2015/07/06/Power-of-4/
3. A number n is a power of 4 if following conditions are met.
a) There is only one bit set in the binary representation of n (or n is a power of 2)
b) The count of zero bits before the (only) set bit is even.
bool isPowerOfFour(unsigned int n){ int count = 0; /*Check if there is only one bit set in n*/ if ( n && !(n&(n-1)) ) { /* count 0 bits before set bit */ while(n > 1) { n >>= 1; count += 1; } /*If count is even then return true else false*/ return (count%2 == 0)? 1 :0; } /* If there are more than 1 bit set then n is not a power of 4*/ return 0;}bool isPowerOfFour(int n){ if(n == 0) return 0; while(n != 1) { if(n%4 != 0) return 0; n = n/4; } return 1;} bool power_of_4(int number) { if (number < 0) { return false; } int pow_4 = 1; while (pow_4 < number && pow_4 > 0) { pow_4 = pow_4 << 2; } return (pow_4 == number); }Read full article from Find whether a given number is a power of 4 or not | GeeksforGeeks
