# Swap Number Without Temporary Variable

Posted: 21 Nov, 2020
Difficulty: Easy

## PROBLEM STATEMENT

#### 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.

##### 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
`````` Approach 1
• 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’.