二叉树的操作

问题：再一次验证自己功底的薄弱，对那些大侠只有仰慕的份。。。

简单说一下自己的感受，递归的实现是个栈，每次函数结束时，退回到上一层，函数结束默认为return。

二叉树的各种非递归实现用到的数据结构是栈。

这次用重温了STL中stack的用法。

 

代码：

#include <iostream>

#include <cstdlib>

#include <stack>

using namespace std;



typedef struct node

{

	char data;

	struct node *left;

	struct node *right;

}*BinTree;



void CreateBTree(BinTree &btree)            //建立二叉树

{

	char c;

	btree=(BinTree)malloc(sizeof(struct node));

	cin>>c;

	if(!btree)

	{

		cout<<"allocated fail"<<endl;

		exit(-1);

	}

	if(c!='#')

	{

		btree->data=c;

		CreateBTree(btree->left);

		CreateBTree(btree->right);

	}

	else

	{

		btree=NULL;

	}



}

void showBTree(BinTree btree)   //递归前序遍历二叉树

{

	if(btree)

	{

		cout<<btree->data<<" ";

		showBTree(btree->left);

		showBTree(btree->right);

	}

}

void inOrderBTree(BinTree btree)  //递归中序遍历二叉树

{

	if(btree)

	{

		inOrderBTree(btree->left);

		cout<<btree->data<<" ";

		inOrderBTree(btree->right);



	}

}



void postOrderBTree(BinTree btree)  //递归后续遍历二叉树

{

	if(btree)

	{

		postOrderBTree(btree->left);

		postOrderBTree(btree->right);

		cout<<btree->data<<" ";

	}

}



void displayBTree(BinTree btree)   //非递归前序遍历二叉树

{

	stack<BinTree> q;

	if(btree)

	{

	BinTree bt;

	q.push(btree);

	while(!q.empty())

	{

		while(bt=q.top())

		{

			cout<<bt->data<<" ";

			q.push(bt->left);

		}

		q.pop();

		if(!q.empty())

		{

			bt=q.top();

			q.pop();

			q.push(bt->right);

		}

	}

	}

    

}



void iOrder(BinTree btree)  //中序非递归遍历

{

	BinTree bt=NULL;

	stack<BinTree> s;

	s.push(btree);

	while(!s.empty())

	{

		while(bt=s.top())

		{

			s.push(bt->left);

		}

		s.pop();

		if(!s.empty())

		{

			bt=s.top();

			cout<<bt->data<<" ";

			s.pop();

			s.push(bt->right);

		}

	}



}



void pOrder(BinTree btree)

{

	stack<BinTree> s;

	BinTree cur=NULL;

	BinTree pre=NULL;

	s.push(btree);

	while(!s.empty())

	{

		cur=s.top();

		if((cur->left==NULL&&cur->right==NULL)||(pre!=NULL&&(pre==cur->left||pre==cur->right)))

		{

			cout<<cur->data<<" ";

			s.pop();

			pre=cur;

		}

		else

		{

			if(cur->right)

				s.push(cur->right);

			if(cur->left)

				s.push(cur->left);		

		}

	}

}



int main()

{

	BinTree bt;

	cout<<"create bintree:"<<endl;

	CreateBTree(bt);



	cout<<"前序遍历二叉树:"<<endl;

	showBTree(bt);

	cout<<endl;

	cout<<"前序非递归遍历:"<<endl;

	displayBTree(bt);

	cout<<endl;



	cout<<"中序遍历二叉树:"<<endl;

	inOrderBTree(bt);

	cout<<endl;

	cout<<"中序非递归遍历二叉树："<<endl;

	iOrder(bt);

	cout<<endl;



	cout<<"后序遍历二叉树："<<endl;

	postOrderBTree(bt);

	cout<<endl;

	cout<<"后序非递归遍历:"<<endl;

	pOrder(bt);

	cout<<endl;

	return 0;

}

运行结果: