二叉树的七种遍历方式以及按行打印

void preorder_digui(TreeNode* pRoot, vector<int> &preorder_digui_re)
{
if (pRoot != NULL)
{
preorder_digui_re.push_back(pRoot->val);
if (pRoot->left)
preorder_digui(pRoot->left, preorder_digui_re);
if (pRoot->right)
preorder_digui(pRoot->right, preorder_digui_re);
}
}

void preorder_while(TreeNode* pRoot, vector<int> &preorder_while_re)
{
stack <TreeNode*>stack1;
while (pRoot || !stack1.empty())
{
if (pRoot == NULL)
{
pRoot = stack1.top();
stack1.pop();
}
if (pRoot != NULL)
{
preorder_while_re.push_back(pRoot->val);
if (pRoot->right)
stack1.push(pRoot->right);
pRoot = pRoot->left;
}
}
}

void inorder_digui(TreeNode* pRoot, vector<int> &inorder_digui_re)
{
if (pRoot != NULL)
{
if (pRoot->left)
inorder_digui(pRoot->left, inorder_digui_re);
inorder_digui_re.push_back(pRoot->val);
if (pRoot->right)
inorder_digui(pRoot->right, inorder_digui_re);
}
}

void inorder_while(TreeNode* pRoot, vector<int> &inorder_while_re)
{
stack<TreeNode*>stack1;
while (pRoot || !stack1.empty())
{
while (pRoot)
{
stack1.push(pRoot);
pRoot = pRoot->left;
}
pRoot = stack1.top();
stack1.pop();
inorder_while_re.push_back(pRoot->val);
pRoot = pRoot->right;
}
}

void afterorder_digui(TreeNode* pRoot, vector<int> &afterorder_digui_re)
{
if (pRoot != NULL)
{
if (pRoot->left)
afterorder_digui(pRoot->left, afterorder_digui_re);
if (pRoot->right)
afterorder_digui(pRoot->right, afterorder_digui_re);
afterorder_digui_re.push_back(pRoot->val);
}
}

void afterorder_while(TreeNode* pRoot, vector<int> &afterorder_while_re)
{
stack <TreeNode*>stack1;
stack1.push(pRoot);
stack1.push(pRoot);
while (!stack1.empty())
{
pRoot = stack1.top();
stack1.pop();
if (!stack1.empty() && stack1.top() == pRoot)
{
if (pRoot->right)
{
stack1.push(pRoot->right);
stack1.push(pRoot->right);
}
if (pRoot->left)
{
stack1.push(pRoot->left);
stack1.push(pRoot->left);
}
}
else
afterorder_while_re.push_back(pRoot->val);
}
}

void kuandu_while(TreeNode *pRoot, vector<int>&kuandu_while_re)
{
queue<TreeNode*>queue1;
queue1.push(pRoot);
kuandu_while_re.push_back(pRoot->val);
while (!queue1.empty())
{
queue<TreeNode*>queue2;
while (!queue1.empty())
{
pRoot = queue1.front();
queue1.pop();
if (pRoot->left)
{
kuandu_while_re.push_back(pRoot->left->val);
queue2.push(pRoot->left);
}
if (pRoot->right)
{
kuandu_while_re.push_back(pRoot->right->val);
queue2.push(pRoot->right);
}
}
queue1 = queue2;
}
}

void kuandu_hang(TreeNode *pRoot, vector<vector<int> > &kuandu_hang_re)
{
queue<TreeNode*>queue1;
queue1.push(pRoot);
vector<int>re;
re.push_back(pRoot->val);
kuandu_hang_re.push_back(re);
while (!queue1.empty())
{
queue<TreeNode*>queue2;
vector<int>re;
while (!queue1.empty())
{
pRoot = queue1.front();
queue1.pop();
if (pRoot->left)
{
re.push_back(pRoot->left->val);
queue2.push(pRoot->left);
}
if (pRoot->right)
{
re.push_back(pRoot->right->val);
queue2.push(pRoot->right);
}
}
kuandu_hang_re.push_back(re);
queue1 = queue2;
}
}