371.sum-of-two-integers.cpp

//  Tag: Math, Bit Manipulation
//  Time: O(1)
//  Space: O(1)
//  Ref: -
//  Note: -

//  Given two integers a and b, return the sum of the two integers without using the operators + and -.
//   
//  Example 1:
//  Input: a = 1, b = 2
//  Output: 3
//  Example 2:
//  Input: a = 2, b = 3
//  Output: 5
//  
//   
//  Constraints:
//  
//  -1000 <= a, b <= 1000
//  
//  

class Solution {
public:
    int getSum(int a, int b) {
        return b==0? a:getSum(a^b, (a&b)<<1);
    }
};

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