100. Same Tree (Tree)

 1 class Solution {
 2     public boolean isSameTree(TreeNode p, TreeNode q) {
 3         if(p == null && q == null) {
 4             return true;
 5         }else if (p== null && q != null) {
 6             return false;
 7         }else if(p != null && q == null) {
 8             return false;
 9         }
10         if(p.val != q.val) {
11             return false;
12         }else {
13             return(isSameTree(p.left, q.left) && isSameTree(p.right, q.right));
14         }
15         
16     }
17 }