1 public class Solution {
 2     public boolean isSameTree(TreeNode p, TreeNode q) {
 3         if(p==null) return q==null;
 4         if(q==null) return p==null;
 5         if(p.val==q.val){
 6             return isSameTree(p.left,q.left)&&isSameTree(p.right,q.right);
 7         }
 8         else return false;
 9     }
10 }