Description

Write a function that add two numbers A and B.

Clarification

Are a and b both 32-bit integers?

• Yes.

Can I use bit operation?

• Sure you can.

Challenge

Of course you can just return a + b to get accepted. But Can you challenge not do it like that?(You should not use + or any arithmetic operators.)

其实这道题就是让你写一个方法去计算A+B的和是多少。它的建议是可以直接返回 A + B 但是它建议不用算术运算符去完成。

Simple

public class Solution {
	
	public int aplusb(int a, int b) {
		return a + b;
	}
}

Efficient

public class Solution {
	
	public int aplusb(int a, int b) {
		if(b == 0){
			return a;
		}
		int aa = a ^ b;
		int bb = (a & b) << 1;
		return (aa, bb);
	}
}

Notice

不进位的两数和可以通过 SUM = A ^ B 来计算
需要进位的两数和需要通过 SUM = (A & B) << 1来计算