public/subjects/findpairs/README.md

Find Pairs

Instructions

Write a program that finds all pairs of elements in an integer array that sum up to a given target value. The program should output a list of pairs, each representing the indices of the elements that form the pair.

In this exercise you must take in consideration the following:

• Ensure it's possible to have positive or negative integers in the array.
• Ensure each element is used only once in a pair, although the element can be repeated in different pairs.
• Allow for multiple pairs to sum up to the target value.
• The output messages should follow the one given in the examples bellow.
• Return the message "No pairs found." when no pair is present.
• Return the message "Invalid target sum." if the target is invalid.
• Return the message "Invalid number: " if the number in the array is invalid.
• For any input format that deviates from the specified format "[1, 2, 3, 4, 5]" "6", the program will return an "Invalid input." error message.

Let's consider the input arr = [1, 2, 3, 4, 5] and the target sum targetSum = 6. When we run the program, the findPairs() function will search for pairs in the array that sum up to targetSum.

Here is some example of outputs:

$ go run . "[1, 2, 3, 4, 5]" "6"
Pairs with sum 6: [[0 4] [1 3]]
$ go run . "[-1, 2, -3, 4, -5]" "1"
Pairs with sum 1: [[0 1] [2 3]]
$ go run . "[1, 2, 3, 4, 5]" "10"
No pairs found.
$ go run . "[-1, -2, -3, -4, -5]" "-5"
Pairs with sum -5: [[0 3] [1 2]]
$ go run . "[1, 2, 3, 4, 20, -4, 5]" "2 5"
Invalid target sum.
$ go run . "[1, 2, 3, 4, 20, p, 5]" "5"
Invalid number: p
$ go run . "[1, 2, 3, 4" "5"
Invalid input.
$ go run . "1, 2, 3, 4" "5"
Invalid input.
$