HackerRank Blocks problem solution in ruby

In this HackerRank Blocks problem solution in ruby programming, Higher-order functions are one of the key components of functional programming. A higher-order function is a tool that takes other functions as parameters or returns them as a result.

Blocks are nameless methods that can be passed to another method as a parameter.

Passing a block to a method is a great way of data abstraction.

Blocks can either be defined with a keyword do … end or curly braces { … }.

Example:

a). Passing a block to a method that takes no parameter

CODE

def call_block

    puts “Start of method.”

    yield

    puts “End of method.”

end 

call_block do 

    puts “I am inside call_block method.”

end

OUTPUT

Start of method.

I am inside call_block method.

End of method.

In this example, a block is passed to the call_block method.

To invoke this block inside the method, we used a keyword, yield.

Calling yield will execute the code within the block that is provided to the method.

b). Passing a block to a method that takes one or more parameters.

CODE

def calculate(a,b)

    yield(a, b)

end

puts calculate(15, 10) {|a, b| a – b}   

OUTPUT

5

In this example, we have defined a method calculate that takes two parameters a and b.

The yield statement invokes the block with parameters a and b, and executes it.

Task

You are given a partially complete code. Your task is to fill in the blanks (_______).

The factorial method computes: n! { n x n – 1 x … 2 x 1 }.

Problem solution.

def factorial
    yield
end

n = gets.to_i
factorial do 
    puts "#{(1..n).inject(:*) || 1}"
end

Second solution.

def factorial(n)
    x = (1..n).inject(:*) || 1
    yield(x)
end

n = gets.to_i
factorial(n) do |x|
    puts x
end