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.
int getSum(int a, int b) { int ans; while(b) { ans = a^b; b = (a&b)<<1; a = ans; } return ans; }
参考：
http://blog.csdn.net/hackbuteer1/article/details/7390093
原文：http://www.cnblogs.com/wxisme/p/5940679.html