二叉樹遍歷遞歸方式實現

2018.11.15

前序遍歷：根->左->右

中序遍歷：左->根->右

後序遍歷：左->右->根

//二叉樹遍歷遞歸方式實現
//2018.11.15 青春如詩
#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
typedef char ElementType;
typedef struct TreeNode *BinTree;
typedef BinTree Position;
struct TreeNode
{
	ElementType Data;
	BinTree Left;
	BinTree Right;
};
//判斷二叉樹是否爲空
bool IsEmpty(BinTree BT)
{
	return BT==NULL;
}
//創建節點
BinTree CreateTreeNode(char ch)
{
	BinTree BT = (BinTree)malloc(sizeof(struct TreeNode));
	BT->Data=ch;
	BT->Left = NULL;
	BT->Right = NULL;
	return BT;
}
//創建二叉樹
BinTree CreateBinTree()
{
	BinTree BT = CreateTreeNode('A');

	BT->Left = CreateTreeNode('B');

	BT->Right = CreateTreeNode('C');
	
	BT->Left->Left = CreateTreeNode('D');
	BT->Left->Right = CreateTreeNode('F');
	BT->Right->Left = CreateTreeNode('G');
	BT->Right->Right = CreateTreeNode('I');
	BT->Left->Right->Left = CreateTreeNode('E');
	BT->Right->Left->Right = CreateTreeNode('H');
	return BT;
}


void DeleteTree(BinTree *BT)
{
	if (*BT)
	{
		DeleteTree(&((*BT)->Left));
		DeleteTree(&((*BT)->Right));
		*BT = NULL;
		free(*BT);
	}
}

//先序遍歷
void PreOrderTraversal(BinTree BT)
{
	if (BT)
	{
		printf("%c->", BT->Data);
		PreOrderTraversal(BT->Left);
		PreOrderTraversal(BT->Right);
	}
}
//中序遍歷
void InOrderTraversal(BinTree BT)
{
	if (BT)
	{
		InOrderTraversal(BT->Left);
		printf("%c->", BT->Data);
		InOrderTraversal(BT->Right);
	}
}
//後序遍歷
void PostOrderTraversal(BinTree BT)
{
	if (BT)
	{
		PostOrderTraversal(BT->Left);
		PostOrderTraversal(BT->Right);
		printf("%c->", BT->Data);
	}
}

int main()
{
	BinTree BT = CreateBinTree();
	printf("先序遍歷：\n");
	PreOrderTraversal(BT);
	printf("\n後序遍歷:\n");
	InOrderTraversal(BT);
	printf("\n後序遍歷:\n");
	PostOrderTraversal(BT);
	DeleteTree(&BT);
	return 0;
}