二叉樹-非遞歸遍歷（先、中、後）

#include<iostream>
#include<malloc.h>
#include<stdio.h>
#define  MAXSIZE  20  //最多結點個數
using namespace std;

/*二叉鏈表*/
typedef struct bnode{
	char data;
	struct bnode *lchild,*rchild;
}Bnode,* BTree;

/*順序棧*/
typedef BTree DataType;
typedef struct{	
	DataType data[MAXSIZE];
	int top;
}SeqStack,* PSeqStack;

PSeqStack Init_SeqStack(void);				//建空棧
void Push_SeqStack(PSeqStack S,DataType x);	//入棧
int Empty_SeqStack(PSeqStack S);			//判斷棧是否爲空
void Pop_SeqStack(PSeqStack S,DataType * y);//出棧
void Destroy_SeqStack(PSeqStack * S);		//銷燬棧

BTree CreateBinTree(void);	//先序創建二叉樹

void NRPreOrder(BTree t);	//非遞歸先序遍歷
void NRInOrder(BTree t);	//非遞歸中序遍歷
void NRPostOrder(BTree t);	//非遞歸後序遍歷

/*主函數*/
int main(){
	cout<<"\n請按先序次序輸入各結點的值，以#表示空樹(輸入時可連續輸入):\n";
	BTree T=CreateBinTree();
	if(!T){
		cout<<"\n未建立樹，請先建樹！";
		return 0;
	}
	cout<<"\n\n非遞歸先序遍歷:";
	NRPreOrder(T);
	cout<<"\n非遞歸中序遍歷:";
	NRInOrder(T);
	cout<<"\n非遞歸後序遍歷:";
	NRPostOrder(T);

	return 1;
}


/******************************順序棧的一些基本操作******************************/
/*建空棧*/
PSeqStack Init_SeqStack(void){
	PSeqStack S;
	S=(PSeqStack)malloc(sizeof(SeqStack));
	if(S){
		S->top = -1;//表示空棧
	}
	return S;
}
/*入棧*/
void Push_SeqStack(PSeqStack S,DataType x){
	if(S->top == MAXSIZE-1){
		cout<<"棧滿不能入棧！";
	}else{
		S->top++;
		S->data[S->top]=x;	
	}
}
/*判斷棧是否爲空*/
int Empty_SeqStack(PSeqStack S){
	if(S->top == -1)
		return 1;
	else
		return 0;
}
/*出棧*/
void Pop_SeqStack(PSeqStack S,DataType * y){
	if(Empty_SeqStack(S)){
		cout<<"棧空不能出棧！";
	}else{
		* y=S->data[S->top];
		S->top--;	
	}
}
/*銷燬棧*/
void Destroy_SeqStack(PSeqStack * S){
	if(* S)
		free(* S);
	* S=NULL;
}


/*先序創建二叉樹*/
BTree CreateBinTree(void){
	BTree t;
	char ch=getchar();
	if(ch=='#')
		t=NULL;//讀入#時，將相應節點指針置空
	else{
		t=(Bnode *)malloc(sizeof(Bnode));
		t->data=ch;
		t->lchild=CreateBinTree();//構造二叉樹的左子樹
		t->rchild=CreateBinTree();//構造二叉樹的右子樹
	}
	return t;
}


/******************************非遞歸******************************/
void NRPreOrder(BTree t){//非遞歸先序遍歷
	BTree p=t;
	PSeqStack S=Init_SeqStack();

	while(p || !Empty_SeqStack(S)){
		if(p){
			cout<<p->data<<" ";
			Push_SeqStack(S,p);
			p=p->lchild;
		}else{
			Pop_SeqStack(S,&p);
			p=p->rchild;
		}
	}
	Destroy_SeqStack(&S);
}

void NRInOrder(BTree t){//非遞歸中序遍歷
	BTree p=t;
	PSeqStack S=Init_SeqStack();

	while(p || !Empty_SeqStack(S)){
		if(p){
			Push_SeqStack(S,p);
			p=p->lchild;
		}else{
			Pop_SeqStack(S,&p);
			cout<<p->data<<" ";
			p=p->rchild;
		}
	}
	Destroy_SeqStack(&S);
}

void NRPostOrder(BTree t){//非遞歸後序遍歷
    BTree p=t;
	PSeqStack S1=Init_SeqStack();
	PSeqStack S2=Init_SeqStack();

	while(p || !Empty_SeqStack(S2)){
		if(p){
			Push_SeqStack(S1,p);

			Push_SeqStack(S2,p);
			p=p->rchild;
		}else{
			Pop_SeqStack(S2,&p);
			p=p->lchild;
		}
	}
	while(!Empty_SeqStack(S1)){
		Pop_SeqStack(S1,&p);
		cout<<p->data<<" ";
	}
	Destroy_SeqStack(&S1);
	Destroy_SeqStack(&S2);
}