371. 两整数之和
     不使用运算符 + 和 - ​​​​​​​，计算两整数 ​​​​​​​a 、b ​​​​​​​之和。

示例 1:
	输入: a = 1, b = 2
	输出: 3
示例 2:
	输入: a = -2, b = 3
	输出: 1

class Solution {
    public int getSum(int a, int b) {
        int carry = a & b;
        int sumNoCarry =  a ^ b;
        int temp1 = carry;
        while(temp1 != 0){
            carry = temp1 << 1;
            temp1 = carry & sumNoCarry;
            sumNoCarry = carry ^ sumNoCarry;
        }
        return sumNoCarry;
    }
}

总结

        carry = carry & sumNoCarry;
        sumNoCarry = carry ^ sumNoCarry;

这么写是错的，因为会把carry进位数覆盖掉，而这个数我们要用两回。