rassoc

## competition.rb
# 0.53 s, 31424 kb
$memo = {}

def collatz(n)
    return $memo[n] if $memo[n]
	$memo[n] = case
        when n == 1  then 1
        when n.even? then 1 + collatz(n.div 2)
        else              1 + collatz(3 * n + 1)
        end
	# 0.53 s, 31424 kb
	$memo = {}

	def collatz(n)
	return $memo[n] if $memo[n]
	$memo[n] = case
	when n == 1 then 1
	when n.even? then 1 + collatz(n.div 2)
	else 1 + collatz(3 * n + 1)
	end