leetcode371. 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.

//solution 1

int getSum(int a, int b) { if(b) { int c = getSum((a^b), (a&b)<<1); return c; } return a; }

//solution 2

int getSum(int a, int b) { int carry; while (b != 0) { carry = (a&b)<<1; a = a^b; b = carry; } return a; }

// ^表示异或，&是按位与，<<表示左移 //&&和||是逻辑运算符，&和|是位运算符。 //carry控制a和b变化前取值，利用也是类似于递归原理。