Pair Sum Problem Statement

Given an integer array ARR of size N and an integer S, your goal is to return a list of all pairs of elements such that the sum of elements of each pair equals S.

Example:

Input:

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

Output:

[2, 5] [3, 4]

Explanation:

The pairs (2, 5) and (3, 4) are the pairs whose sums are equal to 7, sorted according to the given rules.

Constraints:

1

Question

Pair Sum Problem Statement

Given an integer array ARR of size N and an integer S, your goal is to return a list of all pairs of elements such that the sum of elements of each pair equals S.

Example:

Input:

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

Output:

[2, 5]
[3, 4]

Explanation:

The pairs (2, 5) and (3, 4) are the pairs whose sums are equal to 7, sorted according to the given rules.

Constraints:

1 <= N <= 10^4
-10^5 <= ARR[i] <= 10^5
-2 * 10^5 <= S <= 2 * 10^5
Time Limit: 1 sec

Note:

Each pair should be sorted such that the first value is less than or equal to the second value, and the list of pairs should be sorted in non-decreasing order based on the first value. In case two pairs have the same first value, the pair with a smaller second value should appear first.

Accepted Answer

Return pairs of elements in an array whose sum equals a given integer, sorted in non-decreasing order.

Iterate through the array and use a hashmap to store the elements and their indices.
For each element, check if the complement (S - element) exists in the hashmap.
If it exists, add the pair to the result list and sort the pairs based on the rules provided.