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.