572

ruby/572-Subtree-of-Another-Tree.rb

@@ -0,0 +1,24 @@
+def is_subtree(root, sub_root)
+ return true if root.nil? && sub_root.nil?
+ return true if sub_root.nil?
+ return false if root.nil?
+
+ if same_tree?(root, sub_root)
+ true
+ else
+ is_subtree(root.left, sub_root) ||
+ is_subtree(root.right, sub_root)
+ end
+end
+
+def same_tree?(p, q)
+ if p.nil? && q.nil?
+ true
+ elsif p && q
+ (p.val == q.val) &&
+ same_tree?(p.left, q.left) &&
+ same_tree?(p.right, q.right)
+ else
+ false
+ end
+end