3064. Guess the Number Using Bitwise Questions I

There is a number n that you have to find.

There is also a pre-defined API int commonSetBits(int num), which returns the number of bits where both n and num are 1 in that position of their binary representation. In other words, it returns the number of set bits in n & num, where & is the bitwise AND operator.

Return the number n.

/** 
 * Definition of commonSetBits API.
 * int commonSetBits(int num);
 */

class Solution {
public:
    int findNumber() {
        int res = 0, bit = 1;
        for(int i = 0; i < 32; i++) {
            if(commonSetBits(bit)) res |= bit;
            bit<<=1;
        }
        return res;
    }
};