LeetCode 371 : Sum of Two Integers(Java)

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于 2016-07-15 10:05:20 发布

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题目：
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：用异或算不带进位的和，用与并左移一位来算进位，再把两者相加即可，直到进位为全0。递归的解法如下：

public class Solution {
    public int getSum(int a, int b) {
        if(b==0) return a;

        int sum = a ^ b;
        int carry = (a & b) << 1;

        return getSum(sum, carry);
    }
}