Same Tree

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    bool isSameTree(TreeNode* p, TreeNode* q) {
        if(!p && !q)
            return true;
        else if(!p || !q)
            return false;
            
        return (p->val == q->val) && isSameTree(p->left, q->left) && isSameTree(p->right, q->right);
    }
};

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    bool isSameTree(TreeNode* p, TreeNode* q) {
        stack<TreeNode *> s;
        s.push(q);
        s.push(p);
        
        while(!s.empty())
        {
            TreeNode *pTmp = s.top();
            s.pop();
            TreeNode *qTmp = s.top();
            s.pop();
            
            if(!pTmp && ! qTmp)
                continue;
            if(!pTmp || !qTmp)
                return false;
                
            if(pTmp->val == qTmp->val)
            {
                s.push(qTmp->right);
                s.push(pTmp->right);
                s.push(qTmp->left);
                s.push(pTmp->left);
            }
            else
                return false;
        }
        
        return true;
    }
};