Is Same Binary Tree

IsSameBinaryTree.java

/**
 * 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;
        
        return isSameTreeHelper(p, q);
        
    }
    
    public boolean isSameTreeHelper(TreeNode p, TreeNode q){
        if (p == null && q == null) return true;
        
        if (p != null && q != null){
            if (p.val != q.val){
                return false;
            }
            
            if (!isSameTreeHelper(p.left, q.left)){
                return false;
            }
            
            return (isSameTreeHelper(p.right, q.right));
        }
        
        return false;
    }
}