100. Same Tree

/**
 * 100. Same Tree
 * 
 * Problem Description:
 * 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. 
 * 
 * Definition for a binary tree node.
 * 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) return false;
        if(p.val == q.val)
            return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
        return false;
    }
}