二叉樹詳解：創建、前中後序非遞歸遍歷、DFS、BFS、樹的深度

typedef struct BiNode
{
	int data;
	struct BiNode *lChild;
	struct BiNode *rChild;
}*BiTree;

typedef struct MarkNode     //保存標記信息的節點
{
	BiNode *node;
	bool tag;              //  true：表示節點node的左右子樹已經都被訪問
}MarkNode;

//構建二叉樹
void Create(BiTree &T)
{
	char ch;
	cin >> ch;
	if (ch == '#')     //如果到了葉子節點，接下來的左、右子樹分別賦值爲#
	{
		T = NULL;
	}
	else
	{
		T = (BiNode*)malloc(sizeof(BiNode));
		T->data = ch;
		Create(T->lChild);  //遞歸創建左子樹
		Create(T->rChild);  //遞歸創建右子樹
	}
}

// 非遞歸前序遍歷
void PreOrder(BiTree T)
{
	if (T == NULL) return;
	stack<BiNode*> s;
	BiNode *p = T;
	s.push(p);
	while (!s.empty())
	{
		p = s.top();
		s.pop();

		while (p != NULL) 
		{
			printf("%c  ", p->data);
			if (p->rChild != NULL)
			{
				s.push(p->rChild);
			}
			p = p->lChild;
		}
	}
	cout << endl;
}

// 非遞歸中序遍歷  
void InOrder(BiTree T)
{
	if (T == NULL)return;
	stack<BiNode*> s;//聲明一個棧存儲節點
	BiNode *p = T;
	while (!s.empty() || p!=NULL)
	{
		while (p!=NULL)
		{
			s.push(p);//一直存儲左節點
			p = p->lChild;
		}
		p = s.top();
		s.pop();//該節點出棧
		printf("%c  ", p->data);//不存在左節點，輸出該節點		
		p = p->rChild;//查找該節點的右子樹
	}
	cout << endl;
}

// 非遞歸後序遍歷
void PostOrder(BiTree T)
{
        if (T == NULL) return;
	stack<MarkNode> s;
	BiNode *p = T;
	while (p != NULL || !s.empty())
	{
		while (p != NULL)
		{
			MarkNode mark;
			mark.node = p;
			mark.tag = false;
			s.push(mark);
			p = p->lChild;
		}
		while (!s.empty() && s.top().tag)
		{
			printf("%c  ",s.top().node->data);
			s.pop();
		}
		if (!s.empty())
		{
			s.top().tag = true;
			p = s.top().node->rChild;
		}
	}
	cout << endl;
}

//廣度優先遍歷BFS - 隊列
void BFS(BiTree T)
{
	if (T == NULL)
	{
		return;
	}
	queue<BiNode*> q;
	BiNode* p = T;
	q.push(p);
	while (!q.empty())
	{
		p = q.front();
		q.pop();
		printf("%c  ", p->data);
		if (p->lChild)
		{
			q.push(p->lChild);
		}
		if (p->rChild)
		{
			q.push(p->rChild);
		}
	}
	cout << endl;
}

//深度優先遍歷DFS - 棧
void DFS(BiTree T)
{
	if (T == NULL) return;
	stack<BiNode*> s;
	BiNode* p = T;
	s.push(p);
	while (!s.empty())
	{
		p = s.top();
		s.pop();
		printf("%c  ", p->data);
		if (p->rChild)
		{
			s.push(p->rChild);
		}
		if (p->lChild)
		{
			s.push(p->lChild);
		}		
	}
	cout << endl;
}

//樹的深度
int depth(BiTree T)
{
	if (T == NULL)
	{
		return 0;
	}		                                                                       
	else
	{
		int left = depth(T->lChild) + 1;
		int right = depth(T->rChild) + 1;
		return left > right ? left : right;
	}
}

int main()
{
	//測試數據：
	//ABD##E##CF##G##   
	//AB##C##
	BiTree T = NULL;  
	
	Create(T);
	cout << "前序遍歷：" << endl;
	PreOrder(T);
	cout << "中序遍歷：" << endl;
	InOrder(T);
	cout << "後序遍歷：" << endl;
	PostOrder(T);
	cout << "廣度優先遍歷：" << endl;
	BFS(T);
	cout << "深度優先遍歷：" << endl;
	DFS(T);
	cout << "樹的深度：" << endl;
	cout << depth(T) << endl;

	system("pause");
	return 0;
}