pairwise_max_product.rb

require 'bigdecimal'
# Input the number of numbers
n = readline
# Input the list of numbers
array_list = readline.split(' ')

# Initializing the variables
max1 = BigDecimal("0")
max2 = BigDecimal("0")
min1 = BigDecimal("0")
min2 = BigDecimal("0")
min1_index = 0
max1_index = 0


# Finding the Biggest and Smallest Number and storing their index
array_list.each_with_index do |value, index|
    if BigDecimal(value) > 0
        if max1 < BigDecimal(value)
            max1 = BigDecimal(value) 
            max1_index = index
        end
    end 
    if BigDecimal(value) < 0
        if min1 < BigDecimal(value)  * -1
            min1 = BigDecimal(value) * -1 
            min1_index = index
        end
    end 
end

#Finding the second biggest and smallest numbers. 
array_list.each_with_index do |value, index|
    if BigDecimal(value) > 0
        max2 = BigDecimal(value) if BigDecimal(value) <= max1 and BigDecimal(value) > max2 and max1_index != index
    end 
    if BigDecimal(value) < 0
        min2 = BigDecimal(value) * -1 if BigDecimal(value) >= min1 * -1 and BigDecimal(value) < min2 * -1 and min1_index != index
    end 
end
#Checking if any of them is 0, else multiplying them accordingly
if( min1 != 0 or min2!= 0 or max1 != 0 or max2 !=0)
    if(max1 * max2 < min1 * min2)
        result1 =  (min1 * min2)
    else
        result1 =  (max1 * max2)
    end
else 
    result1 = min1 * max1
end
#outputting to a format to pass the tests in Coursera
puts result1.to_s("F").split(".")[0]