LintCode A+B问题题目分析代码

class Solution {
    /*
     * param a: The first integer
     * param b: The second integer
     * return: The sum of a and b
     */
    public int aplusb(int a, int b) {
        // write your code here, try to do it without arithmetic operators.
        if(a==0)return b;  
        if(b==0)return a;  
        int x1 = a^b;  
        int x2 = (a&b)<<1;  
        return aplusb(x1,x2); 
    }
};