[LeetCode] Sum of Two Integers

The code is as follows.

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

The above code may be rewritten to make it more readable.

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

c

stands for the carry bit of adding two integers. The sum of two integers can be decomposed into a summation bit (

a & b

) and a carry bit (

a ^ b

). The

<< 1

is to set the carry bit to the correct bit. The above process is repeated until no carry (

c

, stored in

b

, becomes 0). Then the sum is stored in

a

.