check-subtree.java

/** T1 and T2 are two very large binary tree, with T1 much bigger than T2. Determin if T2 is a subtree of T1.
A tree T2 is a subtree of T1 if there exits a node n in T1 such that the subtree of n is identical to T2. 
If you cut off the tree at node n, the two trees would be identical. **/