【leetcode】两整数和

int getSum(int a, int b){
    while(a & b)
    {
        unsigned int val_and = a & b;
        //int val_and = a & b;

        int val_xor = a ^ b;
        val_and <<= 1;
        a = val_and;
        b = val_xor;
    }
    int result = a^b;
    return result;    
}