二叉树三种遍历方式的递归与非递归实现

void preorder(node* root)
{
if (root)
printf(“%d/n”, root->value);
else
return;
preorder(root->left);
preorder(root->right);
}

void preoder(node* root)
{
element* theStack;
void* data;
node* curNode;
CreateStack(&theStack);
Push(&theStack, root);
while(Pop(&theStack, &data))
{
curNode = (node*) data;
if (curNode)
{
printf(“%d/n”, curNode->value);
Push(&theStack, curNode->right);
Push(&theStack, curNode->left);
}
}
DeleteStack(theStack);
}

void InOrder(BiTree T)
{
if (T == NULL)
return;
if (T->lchild)
InOrder(T->lchild);
printf("%d/n", T->value);
if (T->rchild)
InOrder(T->rchild);
}

void InOrder(BiTree T)
{
InitStack(S);
p = T;
while(p || !StackEmpty(S))
{
if (p)
{
Push(S, p);
p = p->lchild;
}
else
{
Pop(S, p);
printf("%d/n", p->value);
p = p->rchild;
}
}
}

void PostOrder(BiTree T)
{
if (T == NULL)
return;
if (T->lchild)
PostOrder(T->lchild);
if (T->rchild)
PostOrder(T->rchild);
printf("%d/n", T->value);
}

TreeNodeElement::TreeNodeElement()//构造函数
{
_value = -1;
_l = NULL;
_r = NULL;
_tag = false;
}

TreeNodeElement::TreeNodeElement(int value)
{
_value = value;
_l = NULL;
_r = NULL;
_tag = false;
}

void PostRetriveATreeWithoutRecurve(TreeNode root,void (* visit)(TreeNode))
{
stack<TreeNode> tree;
while ((root != NULL) || (!tree.empty()))
{
while (root != NULL)
{
tree.push(root);
root = root->_l;
}

if (!tree.empty())
{
root = tree.top();
if (root->_tag) //可以访问
{
visit(root);
tree.pop();
root = NULL; //第二次访问标志其右子树也已经遍历
}
else
{
root->_tag = true;
root = root->_r;
}
}
}
}