Pair Sum Problem Statement

You are given an integer array 'ARR' of size 'N' and an integer 'S'. Your task is to find and return a list of all pairs of elements where each sum of a pair equals 'S'.

Note:

Each pair should be ordered such that the first value is less than or equal to the second value. The list of pairs should be sorted in non-decreasing order based on their first values. If two pairs have the same first value, the pair with the smaller second value should come first.

Input:

N S ARR[0] ARR[1] ... ARR[N-1]

Output:

C x1 y1 x2 y2 ...

Example:

Input:

N = 5, S = 7 ARR = [3, 1, 2, 4, 5]

Output:

[2, 5] [3, 4]

Constraints:

1 ≤ N ≤ 10³

-10⁵ ≤ ARR[i] ≤ 10⁵

-2 * 10⁵ ≤ S ≤ 2 * 10⁵

Time Limit: 1 sec

Note:

You don't need to print the output; just implement the logic to return the required result.

Question

Pair Sum Problem Statement

You are given an integer array 'ARR' of size 'N' and an integer 'S'. Your task is to find and return a list of all pairs of elements where each sum of a pair equals 'S'.

Note:

Each pair should be ordered such that the first value is less than or equal to the second value. The list of pairs should be sorted in non-decreasing order based on their first values. If two pairs have the same first value, the pair with the smaller second value should come first.

Input:

N S
ARR[0] ARR[1] ... ARR[N-1]

Output:

C
x1 y1
x2 y2
...

Example:

Input:

N = 5, S = 7
ARR = [3, 1, 2, 4, 5]

Output:

[2, 5]
[3, 4]

Constraints:

1 ≤ N ≤ 10³
-10⁵ ≤ ARR[i] ≤ 10⁵
-2 * 10⁵ ≤ S ≤ 2 * 10⁵

Time Limit: 1 sec

Note:

You don't need to print the output; just implement the logic to return the required result.

Accepted Answer

Given an array and a target sum, find all pairs of elements that add up to the target sum.

Iterate through the array and for each element, check if the complement (target sum - current element) exists in a hash set.
If the complement exists, add the pair to the result list.
Sort the pairs based on the first element and then the second element.
Handle edge cases like duplicate elements and pairs with the same values.
Example: For input N=5, S=7, ARR=[3, 1, 2, 4, 5], the output should be [2, 5] and [3, 4].