二叉树前中后/层次遍历的递归与非递归形式（c++）

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/* 二叉树前中后/层次遍历的递归与非递归形式  */ //***************   void preOrder1(BinaryTreeNode* pRoot) {     if(pRoot==NULL)        return;     cout<<pRoot->value;     if(pRoot->left!=NULL)        preOrder1(pRoot->left);     if(pRoot->right!=NULL)        preOrder1(pRoot->right); }   void preOrder2(BinaryTreeNode* pRoot) {     stack<BinaryTreeNode*> s;     BinaryTreeNode *p=pRoot;        if(pRoot==NULL)         return;     while(p!=NULL||!s.empty())     {        while(p!=NULL)        {            cout<<p->value<<" ";            s.push(p);            p=p->left;        }        if(!s.empty())        {            p=s.top();            s.pop();            p=p->right;        }     } }   void preOrder2(BinaryTreeNode* pRoot){    if(pRoot==NULL)        return;     stack<BinaryTreeNode*> s;      s.push(root);     BinaryTreeNode* p;     while(!s.empty()){        p = s.top();       cout<<p->data;//遍历根结点         s.pop();         if(p>right){             s.push(p->right);  //先将右子树压栈         }         if(p->left){             s.push(p->left);  //再将左子树压栈         }     } }   //*****************   //中序遍历 void inOrder1(BinaryTreeNode* pRoot) {     if(pRoot==NULL)         return;           if(pRoot->left!=NULL)         inOrder1(pRoot->left);     cout<<pRoot->value;     if(pRoot->right!=NULL)         inOrder1(pRoot->right); }   void inOrder2(BinaryTreeNode* pRoot) {     stack<BinaryTreeNode*> s;     BinaryTreeNode *p=pRoot;        if(pRoot==NULL)         return;     while(p!=NULL||!s.empty())     {        while(p!=NULL)        {            s.push(p);            p=p->left;        }        if(!s.empty())        {            p=s.top();            cout<<p->value<<" ";            s.pop();            p=p->right;        }     } }   //*****************   //后序遍历 void postOrder1(BinaryTreeNode* pRoot) {     if(pRoot==NULL)         return;     postOrder1(pRoot->left);     postOrder1(pRoot->right);     cout<<pRoot->value<<" "; }   void postOrder2(BinaryTreeNode* pRoot) {     stack<BinaryTreeNode*> s;     BinaryTreeNode *cur;     BinaryTreeNode *pre=NULL;//记录上一个输出的节点     s.push(pRoot);//根结点入栈     while(!s.empty())     {         cur=s.top();         if((cur->left==NULL&&cur->right==NULL)||(pre!=NULL&&(pre==cur->left||pre==cur->right)))         {             //左孩子和右孩子同时为空，或者当前结点的左孩子或右孩子已经遍历过了             cout<<cur->value<<" ";             s.pop();             pre=cur;         }         else         {             if(cur->right!=NULL)                 s.push(cur->right);             if(cur->left!=NULL)                 s.push(cur->left);         }     } }   //***************** //层次遍历，使用队列 void PrintFromTopToBottom(BinaryTreeNode* pRoot) {     if(pRoot == NULL)         return;        deque<BinaryTreeNode *> dequeTreeNode;        dequeTreeNode.push_back(pRoot);     while(dequeTreeNode.size())     {         BinaryTreeNode *pNode = dequeTreeNode.front();         dequeTreeNode.pop_front();          cout<<pNode->m_nValue<<" ";         if(pNode->m_pLeft)             dequeTreeNode.push_back(pNode->m_pLeft);            if(pNode->m_pRight)             dequeTreeNode.push_back(pNode->m_pRight);     } }     //深度优先遍历～先序遍历 void dfs(BinaryTreeNode* root){     stack<BinaryTreeNode* *> nodeStack;      nodeStack.push(root);     Node *node;     while(!nodeStack.empty()){        node = nodeStack.top();       cout<<node->data;//遍历根结点         nodeStack.pop();         if(node->rchild){             nodeStack.push(node->rchild);  //先将右子树压栈         }         if(node->lchild){             nodeStack.push(node->lchild);  //再将左子树压栈         }     } }    //广度优先遍历～层次遍历 void bfs(BinaryTreeNode* root){     queue<BinaryTreeNode* *> nodeQueue;      nodeQueue.push(root);     Node *node;     while(!nodeQueue.empty()){         node = nodeQueue.front();         nodeQueue.pop();         cout<<node->data;//遍历根结点         if(node->lchild){             nodeQueue.push(node->lchild);  //先将左子树入队         }         if(node->rchild){             nodeQueue.push(node->rchild);  //再将右子树入队         }     } }