Same Tree

Given two binary trees, write a function to check if they are equal or not.

Two binary trees are considered equal if they are structurally identical and the nodes have the same value.

Solution:
Basic tree traverse + basic non-void recursion. 

/**
 * 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));
    }
}