二叉樹遍歷算法（非遞歸）

#include <iostream>
#include <stack>

using namespace std;

typedef struct BiTNode
{
	char data;
	struct BiTNode *lchild,*rchild;
}BiTNode,*BiTree;

typedef struct BTNode
{
	BiTNode * btNode;
	bool visit;
}*pBTNode;

void CreateBiTree(BiTree* T)
{
	char input;
	cin>>input;

	if(input == '#')
		*T = NULL;
	else
	{
		*T = new BiTNode;
		(*T)->data = input;
		CreateBiTree(&(*T)->lchild);
		CreateBiTree(&(*T)->rchild);
	}
}

void PreOrderTraverse(BiTree T)	
{							
	stack<BiTree> s;
	BiTree p = T;

	while(p!=NULL || !s.empty())
	{
		while(p != NULL)
		{
			cout<<p->data;
			s.push(p);
			p = p->lchild;
		}
		if(!s.empty())
		{
			p = s.top();
			s.pop();
			p = p->rchild;
		}
	}
}

void InOrderTraverse(BiTree T)
{
	stack<BiTree> s;
	BiTree p = T;

	while(p!=NULL || !s.empty())
	{
		while(p!=NULL)
		{
			s.push(p);
			p = p->lchild;
		}

		if(!s.empty())
		{
			p = s.top();
			s.pop();
			cout<<p->data;
			p = p->rchild;
		}
	}
}

void LastOrderTraverse(BiTree T)
{
	stack<pBTNode> s;
	BiTree p =T;
	pBTNode tmp;

	while(p!=NULL || !s.empty())
	{
		while(p!=NULL)
		{
			pBTNode btn = new BTNode;
			btn->btNode = p;
			btn->visit = true;
			s.push(btn);
			p = p->lchild;
		}

		if(!s.empty())
		{
			tmp = s.top();
			s.pop();

			if(tmp->visit == true)
			{
				tmp->visit = false;
				s.push(tmp);
				p = tmp->btNode->rchild;
			}
			else
			{
				cout<<tmp->btNode->data;
				p = NULL;
			}
		}
	}
}

int main()
{
	BiTree myBT;
	CreateBiTree(&myBT);
	cout<<"\n====================Pre Order Traverse======================\n";
	PreOrderTraverse(myBT);
	cout<<"\n====================In Order Traverse======================\n";
	InOrderTraverse(myBT);
	cout<<"\n====================Lase Order Traverse======================\n";
	LastOrderTraverse(myBT);
	return 0;
}

層序遍歷：

層序遍歷需要藉助隊列來實現非遞歸。

void LeverlOrder(BiTree T)
{
	Queue Q;
	InitQueue Q;
	
	BiTree P;
	EnQueue(Q,T);    //根節點入隊列
	
	while(!Q.isEmpty())   //隊列不爲空，則循環
	{
		DeQueue(Q,p);    //隊頭元素出隊
		Visit(p);        //訪問當前p所指向的節點
		
		if(p->lchild != NULL)    // 左子樹不爲空，則左子樹入隊
			EnQueue(Q,p->lchild);
		
		if(P->rchild != NULL)    // 右子樹不爲空，則右子樹入隊   
			EnQueue(Q,p->rchild);			
	}
}

二叉樹深度遍歷：

int TreeDepth(BinaryTreeNode *pTreeNode)
{
	if(!pTreeNode)
		return 0;
		
	int nLeft = TreeDepth(pTreeNode->m_pLeft);
	int nRight = TreeDepth(pTreeNode->m_pRight);
	
	return (nLeft>nRight)?(nLeft + 1) : (nRight + 1);
}