leetcode 371. Sum of Two Integers

371. Sum of Two Integers  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. public class Solution{ public int getSum(int a, int b) { int c = a ^ b; //找出不同部分 int d = a & b ; //找到两个数共同部分 101 & 111 =101 int sum = c + (d<<1); //左移一位相当于乘2 return sum; } } 总结：不用+ 和 - 计算和，联想到计算机底层运算，将数转换成二进制的位操作。