The challenge
Given two integers a, b, find The sum of them, BUT You are not allowed to use the operators + and –
Notes
- The numbers (a,b) may be positive , negative values or zeros .
- Returning value will be an integer .
- Java: the following methods are prohibited: addExact, average, collect, decrement, increment, nextAfter, nextDown, nextUp, reduce, subtractExact, sum, summing .
The following classes are prohibited: BigDecimal and BigInteger .
Examples
1- Add (5,19) ==> return (24)
2- Add (-27,18) ==> return (-9)
3- Add (-14,-16) ==> return (-30)
The solution in Java code
Option 1:
public class Solution {
public static int add(int x, int y) {
if(y == 0) return x;
int er = x ^ y;
int ar = (x & y) << 1;
return add(er, ar);
}
}
Option 2:
import java.util.concurrent.atomic.AtomicInteger;
public class Solution {
public static int add(int a, int b) {
return (int)(new AtomicInteger(a)).addAndGet(b);
}
}
Option 3:
public class Solution {
public static int add(int x, int y) {
return x \u002b y;
}
}
Test cases to validate our solution
import org.junit.Test;
import static org.junit.Assert.assertEquals;
import org.junit.runners.JUnit4;
public class SumTwoIntgers {
@Test
public void checkPositiveValues() {
assertEquals( 3, Solution.add(1,2));
assertEquals(24, Solution.add(5,19));
assertEquals(40, Solution.add(23,17));
}
@Test
public void checkNegativeValues() {
assertEquals( -30, Solution.add(-14,-16));
assertEquals(-226, Solution.add(-50,-176));
assertEquals( -39, Solution.add(-10,-29));
}
@Test
public void checkMixtureValues() {
assertEquals( 0, Solution.add(-13,13));
assertEquals( -9, Solution.add(-27,18));
assertEquals(-60, Solution.add(-90,30));
}
}
