树基本概念作业

1代码

1.1使用递归法创建一棵树

BinTree CreateBTree(string str, int i)
{
	int len;
	BinTree bt;
	bt = new TNode;
	len = str.size();
	if (i > len - 1 || i <= 0) return NULL;
	if (str[i] == '#') return NULL;
	bt->data = str[i];
	bt->lchild = CreateBTree(str, 2 * i);
	bt->rchild = CreateBTree(str, 2 * i + 1);
	return bt;
}

1.2在该树上实现前、中、后序遍历

前序遍历

void PreOrder(BinTree bt)
{
	if (bt != NULL)
	{
		cout << bt->data<<' ';  	//访问根结点
		PreOrder(bt->lchild);
		PreOrder(bt->rchild);
	}
}

中序遍历

void InOrder(BinTree bt)
{
	if (bt != NULL)
	{
		InOrder(bt->lchild);
		cout << bt->data<<' ';  	//访问根结点
		InOrder(bt->rchild);
	}
}

后序遍历

void PostOrder(BinTree bt)
{
	if (bt != NULL)
	{
		PostOrder(bt->lchild);
		PostOrder(bt->rchild);
		cout<<bt->data<<' '; 	//访问根结点
	}
}

2完整代码

#include<iostream>
#include <stdlib.h>
#include <stdio.h>
#include<string>
using namespace std;

typedef struct TNode *Position;
typedef Position BinTree;
struct TNode {
	char data;
	BinTree lchild;
	BinTree rchild;
};//二叉树的结构存储结构声明

BinTree CreateBTree(string str, int i);//创建二叉树
void PostOrder(BinTree bt);//后续遍历
void InOrder(BinTree bt);//中序遍历
void PreOrder(BinTree bt//先序遍历


int main()
{
	string str;
	cin >> str;
	int i=1,j=0;
	BinTree bt=CreateBTree(str,i);
	printf("先序遍历:");
	PreOrder(bt);
	printf("\n");
	printf("中序遍历:");
	InOrder(bt);
	printf("\n");
	printf("后序遍历:");
	PostOrder(bt);
	printf("\n");
	printf("层次遍历:");
	if (bt == NULL) cout << "NULL";
	else {
		for (j = 0; j < str.size() - 2; j++)
			if (str[j] != '#')	cout << str[j] << ' ';
		if (str[j] != '#') cout << str[j];
		if (str[j + 1] != '#') cout << str[j + 1];
	}
	printf("\n");
	system("pause");
	return 0;
}

BinTree CreateBTree(string str, int i)
{
	int len;
	BinTree bt;
	bt = new TNode;
	len = str.size();
	if (i > len - 1 || i <= 0) return NULL;
	if (str[i] == '#') return NULL;
	bt->data = str[i];
	bt->lchild = CreateBTree(str, 2 * i);
	bt->rchild = CreateBTree(str, 2 * i + 1);
	return bt;
}


void PreOrder(BinTree bt)//先序遍历
{
	if (bt != NULL)
	{
		cout << bt->data;  	//访问根结点
		PreOrder(bt->lchild);
		PreOrder(bt->rchild);
	}
}


void InOrder(BinTree bt) //中序遍历
{
	if (bt != NULL)
	{
		InOrder(bt->lchild);
		cout << bt->data;  	//访问根结点
		InOrder(bt->rchild);
	}
}


void PostOrder(BinTree bt)//后续遍历
{
	if (bt != NULL)
	{
		PostOrder(bt->lchild);
		PostOrder(bt->rchild);
		cout<<bt->data; 	//访问根结点
	}
}

3运行结果