readme.md

371. Sum of Two Integers

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

Solution

class Solution:
    def getSum(self, a: int, b: int) -> int:
        # mask to handle negative numbers in Python due to infinite bit length
        mask = 0xFFFFFFFF

        while b != 0:
            # compute the sum without carrying
            xor = (a ^ b) & mask

            # compute the carry, and shift left by 1
            carry = ((a & b) << 1) & mask

            # update a and b
            a = xor
            b = carry

        # handle negative results
        if a > 0x7FFFFFFF:
            return ~(a ^ mask)
        return a

Java solution

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

Thoughts

Time Complexity

O(1): Although this depends on the number of bits in the numbers, since the input constraint limits the values of a and b to a fixed range, the maximum number of iterations is constant (related to the number of bits, which is 32 for standard integer representations).

Space Complexity

O(1): The solution uses only a constant amount of extra space for variables, regardless of the input size.