Array Pair Sum

Function Name: findPairWithGivenSum

Description

Write a function that finds and returns a pair of numbers from a given array of integers that adds up to a given sum. If there are multiple pairs that match the given sum, the function should return the first pair found. If no such pair exists, return an indication that no such pair has been found, such as null or an empty list.

Requirements

• The function should take two parameters: an array of integers and the target sum.
• The function should return an array containing the first pair of integers that add up to the sum, or an empty array if no pair is found.
• The input array may contain positive or negative integers.
• Do not use any built-in array searching methods like 'filter' or 'find'.
• Optimize the function for time complexity.

Examples

If the input array is [1, 2, 3, 4, 5] and the sum is 6, the function should return [1, 5] because 1 and 5 add up to 6.If the input array is [0, -1, 2, -3, 1] and the sum is -2, the function should return [0, -2] since they are the first pair that adds up to -2.If the input array is [1, 2, 4, 4] and the sum is 8, the function should return [4, 4].If there is no pair with the given sum, for example, an array [1, 2, 5] with a sum of 10, it should return [].