Sum of Two Integers

Problem

Return the sum of two integers a and b without using the + or - operators. Use bitwise tricks: XOR gives sum-without-carry, AND-then-shift gives the carry.

Constraints

• −1000 ≤ a, b ≤ 1000

Approach — Core Patterns

This is a Core Patterns problem. The idea: pick the data structure best matched to the constraints and solve it in one clean pass. Work through the reference code below line by line, then re-derive it yourself in the editor — that's how the pattern sticks.

Complexity: see the walkthrough below.

Solution code

Python

class Solution:
    def getSum(self, a, b):
        mask = 0xFFFFFFFF
        while b & mask:
            a, b = a ^ b, (a & b) << 1
        a &= mask
        return a if a <= 0x7FFFFFFF else ~(a ^ mask)

Java

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

Practice it

Reading a solution isn't the same as being able to write it under pressure. Open this problem in the in-browser editor, hide the solution, and solve it from scratch — your code runs against real test cases instantly.