Given an integer N, swap the adjacent bits in the binary representation of the integer, and print the new number formed after swapping.

swap_bits.cpp

#include <iostream>
using namespace std;

#define ui  uint32_t

ui swap_bits(ui n) {
    ui bitval;
    for(int i = 0; i < 32; i+=2) {
        bitval = ((n>>i)&1) | (((n>>(i+1))&1)<<1);
        
        // for only 01 and 10 => bitval == 1, or bitval == 2. We don't care if bits at adjacent placs are 00 or 11.
        if(bitval > 0 && bitval < 3)
            n ^= ((1U<<i) | (1U<<(i+1)));  // xor n's value with 11 at the respective position.
            // same as above: n ^= (3<<i);
    }
    return n;
}

int main() {
    ui t;   cin >> t;
    while(t--) {
        ui n;   cin >> n;
        cout << swap_bits(n) << "\n";
    }
    return 0;
}