merge two binary trees sloved in ruby
class TreeNode
attr_accessor :val, :left, :right
def initialize(val=0, left=nil, right=nil)
@val = val
@left = left
@right = right
end
end
def merge_trees(t1, t2)
return t2 if t1.nil?
return t1 if t2.nil?
t1.val += t2.val
t1.left = merge_trees(t1.left, t2.left)
t1.right = merge trees(t1.right, t2.right)
t1
end