# HackerRank Ruby Enumerable reduce Solution

Hello coders, In this post, you will learn how to solve HackerRank Ruby Enumerable reduce Solution. This problem is a part of the Ruby Tutorial series. One more thing to add, don’t straight away look for the solutions, first try to solve the problems by yourself. If you find any difficulty after trying several times, then look for the solutions.

## HackerRank Ruby Enumerable reduce Solution

Let’s get started with HackerRank Ruby Enumerable reduce Solution

### Problem Statement

A common scenario that arises when using a collection of any sort, is to get perform a single type of operation with all the elements and collect the result.

For example, a sum(array) function might wish to add all the elements passed as the array and return the result.

A generalized abstraction of same functionality is provided in Ruby in the name of reduce (inject is an alias). That is, these methods iterate over a collection and accumulate the value of an operation on elements in a base value using an operator and return that base value in the end.

Let’s take an example for better understanding.

>>> (5..10).inject(1) {|product, n| product * n }
=> 151200

In above example, we have the following elements: a base value 1, an enumerable (5..10), and a block with expressions instructing how to add the calculated value to base value (i.e., multiply the array element to product, where product is initialized with base value)

So the execution follows something like this:

# loop 1
n = 1
product = 1
return value = 1*1

# loop 2
n = 2
product = 1
return value = 1*2

n = 3
product = 2
return value = 2*3

..

As you can notice, the base value is continually updated as the expression loops through the element of container, thus returning the final value of base value as result.

Other examples,

>>> (5..10).reduce(1, :*)   # :* is shorthand for multiplication
=> 151200

Consider an arithmeticogeometric sequence where the nth term of the sequence is denoted by tn = n2 + 1, n >= 0. In this challenge, your task is to complete the sum method which takes an integer n and returns the sum to the n terms of the series.

### HackerRank Ruby Enumerable reduce Solution

def sum_terms(n)
nth_term = (n**2)+1
(1..n).reduce(0){|sum, n| sum+(n**2+1)}
end

Note: This problem (Ruby Enumerable reduce) is generated by HackerRank but the solution is provided by Chase2Learn. This tutorial is only for Educational and Learning purpose.

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