CareerCup

bitwise left to right bitmask scan, and sum those scan with right to left bitwise scan?

if someone suggest better idea? optimization may be dependent on ISA i think

template <typename T>
T rev_bits ( T val )
{
T ret = 0;
T n_bits = sizeof ( val ) * CHAR_BIT;

for ( unsigned i = 0; i < n_bits; ++i ) {
ret = ( ret << 1 ) | ( val & 1 ); // copy the lsb
val >>= 1; //shift right by 1 position
}

return ret;
}

template <typename T>
T rev_bits ( T val )
{
T ret = 0;
T n_bits = sizeof ( val ) * CHAR_BIT;

for ( unsigned i = 0; i < n_bits; ++i ) {
ret = ( ret << 1 ) | ( val & 1 ); // copy the lsb
val >>= 1; //shift right by 1 position
}

return ret;
}

XOR it with all 1's . Since 1 XOR 1 would result 0 and 0 XOR

Sorry I pressed enter quite early

cont...

0 XOR 1 would result in 1