371. Sum of Two Integers （Binary）

https://leetcode.com/problems/sum-of-two-integers/discuss/84277/One-liner-with-detailed-explanation

https://stackoverflow.com/questions/9070937/adding-two-numbers-without-operator-clarification

sum用^把不需要进位的取出
carry把需要进位的用<<实现进位 然后再把sum和carry相加算出进位之后的结果 知道carry为0 就是没有需要进位的了

 

 

class Solution {
    public int getSum(int a, int b) {
        if (b == 0) return a;
        int sum, carry;
        sum = a ^ b;
        carry = (a & b) << 1;
        return getSum(sum, carry);
        
    }
}