Fast & elegant:

int lsb(int x) {
    return x & -x;
}

Tests

int main() {
    cout << lsb(2) << "\n";  //  2 = 0010
    cout << lsb(4) << "\n";  //  4 = 0100
    cout << lsb(6) << "\n";  //  6 = 0110
    cout << lsb(7) << "\n";  //  7 = 0111
    cout << lsb(8) << "\n";  //  8 = 1000
    cout << lsb(12) << "\n"; // 12 = 1100
    return 0;
}

Output

2
4
2
1
8
4

Brute force

// x is a signed 32-bit integer
int lsb(int x) {
    for (int i = 0; i < 30; i++) {
        if (x & (1<<i)) {
            return 1 << i;
        }
    }
    return 0;
}

Output for the new version

2
4
2
1
8
4

Practice

• 231. Power of Two
• 191. Number of 1 Bits

Related concepts

• Two’s complement