03. Same Tree

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public boolean isSameTree(TreeNode p, TreeNode q) {
        if (p==null && q==null) return true;
        if ((p==null && q!=null) || (p!=null && q==null)) return false;
        if (p.val!=q.val) return false;
       
        return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
    }
}