To store whether parity of count is odd
bool odd_c = 0 ; if ( ( ( l & ( 1 << i ) ) != 0 ) && l % 2 == 1 ) odd_c = ( odd_c ^ 1 ) ; if ( ( ( r & ( 1 << i ) ) != 0 ) && r % 2 == 0 ) odd_c = ( odd_c ^ 1 ) ;