Swap Number Without Temporary Variable

Easy

0/40

Average time to solve is 15m

21 upvotes

Asked in companies

Problem statement

Given two variables ‘X’ and ‘Y’. Your task is to swap the number without using a temporary variable or third variable.

Swap means the value of ‘X’ and ‘Y’ must be interchanged. Take an example ‘X’ is 10 and ‘Y’ is 20 so your function must return ‘X’ as a 20 and ‘Y’ as a 10.

Detailed explanation ( Input/output format, Notes, Images )

Input format:

The first line of input contains an integer ‘T’ denoting the number of test cases.

Next ‘T’ lines contain two space-separated integers ‘X’ and ‘Y’ which represent the next ‘T’ test cases.

Output Format

For each test case, return an array/vector that contains two integers ‘X’ and ‘Y’ with a swapped value.

Note :

You do not need to print anything, it has already been taken care of. Just implement the given function.

Constraints:

1 <= T <= 2*10^5
-10^9 <= X,Y <= 10^9

Where ‘T’ is the total number of test cases, ‘X’ and ‘Y’ denotes two given integer variables.

Time limit: 1 second

Sample Input 1:

2
10 12 
-4 -5

Sample Output 1:

12 10
-5 -4

Explanation of sample input 1:

Test Case 1:
Given ‘X’ is 10 and ‘Y’ is 12. After swapping ‘X’ will be 12 and ‘Y’ will be 10.

Test Case 2:
Given ‘X’ is -1 and ‘Y’ is -5. After swapping ‘X’ will be -5 and ‘Y’ will be -4.

Sample Input 2:

2
1 2 
0 -5

Sample Output 2:

2 1
-5 0

Hint 1

Hint 2

Hint 3

Hint 4

Try with arithmetic operations (addition and subtraction)

Approaches (4)

Approach 1

Approach 2

Approach 3

Approach 4

Addition Approach

Idea is to get the sum of given two-variable ‘X’ and ‘Y’ in an ‘X’ = ‘X’ + ‘Y’.
Value of swapped ‘Y’ can get by ‘X’ - ‘Y’ = (‘X’ + ‘Y’) - ‘Y’ = ‘X’
Value of swapped ‘X’ can get by ‘X’ - ‘Y’ = (‘X’ + ‘Y’) - ‘Y’ = (‘X’ + ‘Y’) - ‘X’ = ‘Y’
The current value of ‘Y’ is the initial value of ‘X’
Suppose ‘X’ is 10 and ‘Y’ is 20 then
- ‘X’ = ‘X’ + ‘Y’ = 20+10’
- Swapped value of ‘Y’ is ‘X’- ‘Y’ = 30-20 = 10’
- And the swapped value of ‘X’ is ‘X’ - ‘Y’ = 30-10 = 20’
- So ‘X’ is 20 and ‘Y’ is 10
Return swapped ‘X’ and ‘Y’.

Time Complexity

O(1), We are taking only constant time

Space Complexity

O(1), We are using constant space

(100% EXP penalty)

Swap Number Without Temporary Variable

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