Sum of Two Integers

Problems

Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -.

Example 1

Input: a = 1, b = 2
Output: 3

Example 2

Input: a = -2, b = 3
Output: 1

Optimal Solution

Complexity

• Time: O(n)
• Space: O(1)

public int getSum(int a, int b) {
    if (b == 0) {
        return a;
    }
    int sum = a ^ b;
    int carry = (a & b) << 1;
    return getSum(sum, carry);
}