isSubTree
import java.util.*
class TreeNode {
int val;
TreeNode left;
TreeNode right;
TreeNode(int x) { val = x; }
}
public class Subtree {
public boolean isSubTree(TreeNode T1, TreeNode T2) {
if (T2 == null) return true;
if (T1 == null) return false;
return (isSameTree(T1,T2) || isSubTree(T1.left, T2) || isSubTree(T1.right, T2));
}
public boolean isSameTree(TreeNode T1, TreeNode T2) {
if (T1 == null && T2 == null) return true;
if (T1 == null || T2 == null) return false;
if (T1.val != T2.val) return false;
return (isSameTree(T1.left, T2.left) && isSameTree(T1.right, T2.right));
}
}