6-sum_square_difference.rb

#The sum of the squares of the first ten natural numbers is,
#12 + 22 + ... + 102 = 385
#The square of the sum of the first ten natural numbers is,
#(1 + 2 + ... + 10)2 = 552 = 3025
#Hence the difference between the sum of the squares of the first ten natural numbers and the square of the sum is 3025 − 385 = 2640.
#Find the difference between the sum of the squares of the first one hundred natural numbers and the square of the sum.

#time: 1h

def sum_squares_first_hundred
    sum = 0
    (1..100).each {|n|
        sum += (n * n)
    }
    return sum
end

def square_sum_first_hundred
    sum = 0
    (1..100).each {|n| 
        sum += n
    }
    return sum * sum
end

#puts "diference between sum of the squares and square of the sum => #{sum_squares_first_hundred - square_sum_first_hundred}"
puts "diference between sum of the squares and square of the sum => #{square_sum_first_hundred - sum_squares_first_hundred}"