huangs3@birkhoff:~/BinTree javac TestBinTree.java 
huangs3@birkhoff:~/BinTree java TestBinTree
max(t1)=1  t1=1
max(t2)=2  t2=2
max(t3)=2  t3=(1,2)
max(t4)=1  t4=1
max(t5)=1  t5=([],1)
max(t6)=1  t6=(([],1),[])
max(t7)=2  t7=((1,2),(([],1),[]))
java.lang.IllegalArgumentException: node with both children null
huangs3@birkhoff:~/BinTree