In this challenge, 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 a 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.