LeetCode 371 Sum of Two Integers - Example and Complexity Analysis

Trace a = 2, b = 3 (binary: 10 and 11).

Iteration 1:

• sum = 10 ^ 11 = 01.
• carry = (10 & 11) << 1 = (10) << 1 = 100.
• a = 01, b = 100.

Iteration 2:

• sum = 001 ^ 100 = 101.
• carry = (001 & 100) << 1 = (000) << 1 = 000.
• a = 101, b = 000.

b = 0. Done. Answer: 101 = $5$.

$O(1)$ time (at most 32 iterations for 32-bit integers). $O(1)$ space.