interview_questions.rb

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# Write a function fib() that a takes an integer "n" and returns the n-th fibonacci number
# fib(0) # => 0
# fib(1) # => 1
# fib(2) # => 1
# fib(3) # => 2
# fib(4) # => 3
# ...

def fib(n)
    # write the body of your function here
    if n<=2 
        return 1
    else
      return fib(n-1) + fib(n-2)
    end
end

# run your function through some test cases here
puts fib(1)
puts fib(2)
puts fib(3)
puts fib(4)

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# Calculate factorial n

puts (1..n).inject(1,:*)

# Resursively

def factorial(n)
    return 1 if n <= 1
    n * factorial(n-1)
end

puts factorial(num)

# or this short method in javascript
let fact = (n) => { return n>0 ? n*fact(n-1) : 1 }

console.log(fact(3))


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# FizzBuzz
# Print a string FizzBuzz if a number is devided by 3 and 5. 
# Print Fizz if is devided by 3, prind Buzz if is devided by 5 or just a number
n = 100
(1..n).each do |n|
  puts n%15==0 ? "FizzBuzz" : n%3==0 ? "Fizz" : n%5==0 ? "Buzz" : n
end

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# Write a function that sorts the keys in a hash by the length of the key as a string. For instance, the hash:
#
# { abc: 'hello', 'another_key' => 123, 4567 => 'third' }
# should result in:
#
# ["abc", "4567", "another_key"]

hsh = { abc: 'hello', 'another_key' => 123, 4567 => 'third' }

#The same as hsh.keys.map{ |key| key.to_s }.sort_by{ |key| key.length }
p hsh.keys.map(&:to_s).sort_by(&:length)

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# Write a single line of Ruby code that prints the Fibonacci sequence of any length as an array.

(1..20).inject( [0, 1] ) { | fib | fib << fib.last(2).inject(:+) }

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# Extract substring from a string
a = "hello there"

a[1]                   #=> "e"
a[2, 3]                #=> "llo"
a[2..3]                #=> "ll"