Sum of Two Integers

最新推荐文章于 2022-10-10 23:59:46 发布

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最新推荐文章于 2022-10-10 23:59:46 发布

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分类专栏： LeetCode 文章标签： LeetCode Sum of Two Integers C++

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题目描述：

Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -.

Example:
Given a = 1 and b = 2, return 3.

解题思路：

二进制加法规则
1+1=10
1+0=01
0+1=01
0+0=00
所以本位用异或运算,进位用与后再与下一位进行异或

AC代码如下：

class Solution {
public:
	int getSum(int a, int b) {
		int sum = 0;
		int bit_num = sizeof(int) * 8;
		int ad = 0;
		for (int i = 0; i < bit_num; ++i){
			if ((((1 << i) & a) & ((1 << i) & b)) != 0){
				sum |= ad << i;
				ad = 1;
			}
			else{
				if (((1 << i) & a) != 0){
					sum |= (1 ^ ad) << i;
					ad = 1 & ad;
				}
				else if (((1 << i) &b) != 0){
					sum |= (1 ^ ad) << i;
					ad = 1 & ad;
				}
				else{
					sum |= ad << i;
					ad = 0;
				}
			}
			
		}
		return sum;
	}
};