# HackerRank Ruby Hash - Addition, Deletion, Selection problem solution

In this HackerRank Ruby Hash - Addition, Deletion, Selection problem solution we will show you ways in which we can add key-value pairs to Hash objects, delete keys from them, and retain them based on logic.

Consider the following Hash object:

h = Hash.new

h.default = 0

A new key-value pair can be added using or the store method

h[key] = value

or

h.store(key, value)

An existing key can be deleted using the delete method

h.delete(key)

For destructive selection and deletion, we can use keep_if and delete_if as seen in Array-Selection

> h = {1 => 1, 2 => 4, 3 => 9, 4 => 16, 5 => 25}

=> {1 => 1, 2 => 4, 3 => 9, 4 => 16, 5 => 25}

> h.keep_if {|key, value| key % 2 == 0} # or h.delete_if {|key, value| key % 2 != 0}

=> {2 => 4, 4 => 16}

Note

For non-destructive selection or rejection, we can use select, reject, and drop_while similar to Array-Selection

In this challenge, a hash object called hackerrank is already created. You have to add

A key-value pair [543121, 100] to the hackerrank object using store

Retain all key-value pairs where keys are Integers ( clue : is_a? Integer )

Delete all key-value pairs where keys are even-valued.

## Problem solution.

```# Enter your code here.
hackerrank.store(543121,100)
hackerrank.keep_if {|a,b|  a.is_a? Integer }
hackerrank.delete_if {|a,b| a.even? }```

## Second solution.

```# Enter your code here.
hackerrank.store(543121, 100)
hackerrank.keep_if { | k, v| k.is_a? Integer }
hackerrank.delete_if { | k, v| k % 2 == 0 }
```