【LeetCode 100_二叉树_遍历】Same Tree

解法一：递归

 bool 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;

     if (!isSameTree(p->left, q->left) || !isSameTree(p->right, q->right))
         return false;

     return true;
 }

解法二：非递归

 bool isSameTree(TreeNode* p, TreeNode* q)
 {
     queue<pair<TreeNode*, TreeNode*> > pq_queue;
     pq_queue.push(make_pair(p, q));

     while (!pq_queue.empty()) {
         TreeNode *pTmp = pq_queue.front().first;
         TreeNode *qTmp = pq_queue.front().second;
         pq_queue.pop();

         if (pTmp == NULL && qTmp == NULL)
             continue;
         if (pTmp == NULL || qTmp == NULL)
             return false;
         if (pTmp->val != qTmp->val)
             return false;

         pq_queue.push(make_pair(pTmp->left, qTmp->left));
         pq_queue.push(make_pair(pTmp->right, qTmp->right));
     }
     return true;
 }