http://oj.leetcode.com/problems/same-tree/

SameTree.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;
        if ((p != null) && (q == null)) return false;
        if ((p == null) && (q != null)) return false;
        if (p.val == q.val) {
            return (true && isSameTree(p.left, q.left) && isSameTree(p.right, q.right));
        } 
        return false;
    }
}