二叉树的三种递归遍历算法

二叉树本身是一种递归的数据类型，二叉树的许多操作离不开递归。

include <stdio.h>

include<stdlib.h>

include<stdbool.h>

typedef int TElemtype;

typedef struct BiTNode
{
	TElemtype Data;
	int IfVisited;
	struct BiTNode* Lchild, * Rchild;

}BiTNode;
typedef BiTNode* BiTree;

void PrintTree(BiTree Tree)
{
	printf("%d ", Tree->Data);
}

void PreOrder(BiTree Tree, void(*Visit)(BiTree))
{
	if (Tree) {
		Visit(Tree);
		PreOrder(Tree->Lchild, Visit);
		PreOrder(Tree->Rchild, Visit);
	}

}

void InOrder(BiTree Tree, void(*Visit)(BiTree))
{
	if (Tree)
	{
		InOrder(Tree->Lchild, Visit);
		Visit(Tree);
		InOrder(Tree->Rchild, Visit);
	}
}

void PostOrder(BiTree Tree, void (*Visit)(BiTree))
{
	if (Tree)
	{
		PostOrder(Tree->Lchild, Visit);
		PostOrder(Tree->Rchild, Visit);
		Visit(Tree);
	}
}

BiTree CreateNode(int item)
{
	BiTree t = (BiTree)malloc(sizeof(BiTNode));
	t->Data = item;
	t->IfVisited = false;
	t->Lchild = NULL;
	t->Rchild = NULL;
	return t;
}

  int main()
{
	BiTree  N[9];

	for (int i = 0; i < 9; i++) { N[i] = CreateNode(i); N[i]->IfVisited = 0; }
	N[0]->Lchild = N[1]; N[0]->Rchild = N[2];
	N[1]->Lchild = N[3];
	N[2]->Lchild = N[4]; N[2]->Rchild = N[5];
	N[3]->Rchild = N[6];
	N[6]->Lchild = N[7]; N[6]->Rchild = N[8];
}