CODEWITHSUNDEEP
algorithmswap
Khan
Khan

Reputation: 185

Swapping two numbers using only two variables

How is it performing swapping?

a=a+b
b=a+b
a=b+a

I don't agree that it's swap to a book!!!

The book options include "complements of values of a and b", "negate and b". Hope these options aren't satisfying it too???

Upvotes: 3

Views: 5947

Answers (5)

Ja͢ck
Ja͢ck

Reputation: 173552

The swap is performed using XOR, which is typically written as a plus within a circle (⊕); for example:

a := 5
b := 7

a := a xor b (2)
b := a xor b (5)
a := b xor a (7)

Upvotes: 9

Prateek Sharma
Prateek Sharma

Reputation: 372

We can use XOR (^) for this. Advantage of XOR : As XOR works on bit level, it takes very less amount of time than any other operations. If a = 5 and b = 7 then to swap :

a = a ^ b

b = a ^ b

a = a ^ b

Where '^' means XOR. Result : a = 7 and b = 5

Upvotes: 0

user10212105
user10212105

Reputation:

I recently underwent an interview for java fresher, the interviewer asked me to perform swapping of two numbers (but in one line).

Swapping of two numbers can be performed in one line also, without using a temp variable.

The logic is really simple,

x is added with y in the same line, y is assigned as x which is subtracted by their sum.

after performing this one line arithmetics the numbers were swapped. (only in one line)

public class SwapInOneLine {
public static void main(String[] args) {

    int x = 10; int y = 20;
    System.out.println("Before Swaping: x = " + x + " and y= " + y);
    x = x + y - (y = x);
    System.out.println("After Swaping: x = " + x + " and y= " + y);
}}

output:

Before Swaping: x = 10 and y= 20

After Swaping: x = 20 and y= 10

Upvotes: 0

Satya
Satya

Reputation: 8881

The correct algorithm should be:

a = a + b 
b = a - b
a = a - b

Upvotes: 12

Pankaj Lilan
Pankaj Lilan

Reputation: 4453

Actually, it can be done by two ways:

int a = 5, b = 10;

Using Addition(+) and Subtraction(-)

a = a + b;
b = a - b;
a = a - b;

Using Multiple(*) and Division(/)

a = a * b;
b = a / b;
a = a / b;

Upvotes: -1

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