Ruby Enumerables: ‘any’, ‘all’, ‘none’, and ‘find’ Solution

In this post, we will solve Ruby Enumerables: ‘any’, ‘all’, ‘none’, and ‘find’ HackerRank Solution. This Problem (Ruby Enumerables: ‘any’, ‘all’, ‘none’, and ‘find’) is a part of HackerRank Ruby series.


Ruby offers various enumerables on collections that check for validity of the objects within it.

Consider the following example:

> arr = [1, 2, 3, 4, 5, 6]
=> [1, 2, 3, 4, 5, 6]
> h = {"a" => 1, "b" => 2, "c" => 3}
=> {"a" => 1, "b" => 2, "c" => 3}

The any? method returns true if the block ever returns a value other than false or nil for any element passed to it:

> arr.any? {|a| a % 2 == 0} # checks if any number in the array is even
=> True
> h.any? {|key, value| value.is_a? String} # checks if any value of the Hash object is of the type String
=> False

The all? method returns true if the block never returns false or nil for any element passed to it:

> arr.all? {|a| a.is_a? Integer} # checks if all elements of the array are of the type Integer
=> True
> h.all? {|key, value| key.is_a? String} # checks if all keys of the Hash object are of the type String
=> True

The none? method returns true if the block never returns true for any element passed to it:

> arr.none? {|a| a.nil?} # Checks if none of the elements in the array are of nil type
=> True
> h.none? {|key, value| value < 3} # checks if all values of the Hash object are less than 3
=> False

The find method returns the first element for which block is not false:

> arr.find {|a| a > 5} # returns the first element greater than 5 and `nil` if none satisfies the condition
=> 6
> h.find {|key, value| key == "b"} # returns an Array of the first match [key, value] that satisfies the condition and nil otherwise
=> ["b", 2]


Based on what you’ve learned above, complete the functions declared in your editor below.

Solution – Ruby Enumerables: ‘any’, ‘all’, ‘none’, and ‘find’

def func_any(hash)
  # Check and return true if any key object within the hash is of the type Integer
  # If not found, return false.
  hash.any? {|key,value| key.is_a? Integer}

def func_all(hash)
  # Check and return true if all the values within the hash are Integers and are < 10
  # If not all values satisfy this, return false.
  hash.all? {|key, value| (value.is_a? Integer and value < 10)}

def func_none(hash)
  # Check and return true if none of the values within the hash are nil
  # If any value contains nil, return false.
  hash.none? {|key, value| value.nil? }

def func_find(hash)
  # Check and return the first object that satisfies either of the following properties:
  #   1. There is a [key, value] pair where the key and value are both Integers and the value is < 20 
  #   2. There is a [key, value] pair where the key and value are both Strings and the value starts with `a`.
  hash.find {|key, value| ((key.is_a? Integer and value.is_a? Integer and value < 20) or (key.is_a? String and value.is_a? String and value[0] == 'a'))}

Note: This problem (Ruby Enumerables: ‘any’, ‘all’, ‘none’, and ‘find’) is generated by HackerRank but the solution is provided by CodingBroz. This tutorial is only for Educational and Learning purpose.

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