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def assert_equal(x, y)
raise [x, y].inspect unless x == y
end
class Node
attr_accessor :data, :next
def initialize(data)
@data = data
end
def to_s
"#{data}#{self.next&.to_s}"
end
end
class Solution
def self.run(l1, l2, carry = 0)
return Node.new(carry) if l1.nil? && l2.nil?
return l2 if l1.nil?
return l1 if l2.nil?
sum = l1.data + l2.data + carry
result = Node.new(sum % 10)
result.next = run(l1.next, l2.next, sum / 10);
result
end
end
l1 = Node.new(2)
l1.next = Node.new(4)
l1.next.next = Node.new(3)
l2 = Node.new(5)
l2.next = Node.new(6)
l2.next.next = Node.new(4)
result = Solution.run(l1, l2)
assert_equal result&.data, 7
assert_equal result&.next&.data, 0
assert_equal result&.next&.next.data, 8
l1 = Node.new(9)
l1.next = Node.new(9)
l1.next.next = Node.new(9)
l2 = Node.new(9)
l2.next = Node.new(9)
l2.next.next = Node.new(9)
result = Solution.run(l1, l2)
assert_equal result&.data, 8
assert_equal result&.next&.data, 9
assert_equal result&.next&.next.data, 9
assert_equal result&.next&.next&.next.data, 1
l1 = Node.new(0)
l1.next = Node.new(0)
l1.next.next = Node.new(1)
l2 = Node.new(0)
result = Solution.run(l1, l2)
assert_equal result&.data, 0
assert_equal result&.next&.data, 0
assert_equal result&.next&.next.data, 1
=begin
| 1 | 10 | 100 | 1000 |
| 10^0 | 10^1 | 10^2 | 10^3 |
| 2 | 4 | 3 |
| 5 | 6 | 4 |
x == (2 * 10^0) + (4 * 10^1) + (3 * 10^2)
x == 342
y == (5 * 10^0) + (6 * 10^1) + (4 * 10^2)
y == 465
=end
puts "YAY!"
|
