#include <stdio.h>
#include <stdlib.h>
//節點宣告，資料域、左指標、右指標
typedef struct BiTNode
{
   int data;
   struct BiTNode *Left,*Right;
}BiTNode,*BiTree;
typedef struct SeqStack{
	BiTNode* num[100];
	int top;
}SeqStack;
void InitStack(SeqStack *S){
	S->top = -1;
}
int push(SqStack* S,BitNode* p){
	if(S->top==-1)
	{
		return 0;
	}
	S->top++;
	S->num[S->top] = *p;
	return 1;
}
int pop(SqStack* S,BitNode* p){
	if(S->top ==-1)
		return 0;
	else{
		p = &(S->num[S->top]);
		S->top--;
		return 1;
	}	
}
BiTree CreateBiTree();
void PreOrderTraverse(BiTree root);
void PostOrder(BiTNode *root);
int main(void)
{
   BiTree T;
   int d;
   T = CreateBiTree();//建立
   //PreOrderTraverse(T);
   PostOrder(T);
   return 0;
}
 

先序建立二叉樹

BiTree CreateBiTree()
{
   char a;
   BiTree T;
   scanf("%c",&a);
   if(a=='#')
       T=NULL;
   else
   {
       T = (BiTree)malloc(sizeof(BiTNode));
       T->data = a;
       T->Left = CreateBiTree();
       T->Right = CreateBiTree();
   }
   return T;//返回根節點
}

先序遞迴遍歷一個二叉樹

void PreOrderTraverse(BiTree root){
	if(root!=NULL){
		printf("%c",root->data);
		PreOrderTraverse(root->Left);
		PreOrderTraverse(root->Right);
	}
}

中序遞迴遍歷一個二叉樹

void InOrderTraverse(BiTree root){
	if(root!=NULL){
		InOrderTraverse(root->Left);
		printf("%c",root->data);
		InOrderTraverse(root->Right);
	}
}
 

後序遞迴遍歷一個二叉樹

void PostOrderTraverse(BiTree root){
	if(root!=NULL){
		PostOrderTraverse(root->Left);
		PostOrderTraverse(root->Right);
		printf("%c",root->data);
	}
}

先序非遞迴遍歷一個二叉樹

void PreOrder(BiTree root){
	SeqStack* S = (SeqStack*)malloc(sizeof(SeqStack));
	InitStack(S);
	BiTNode* p;
	p = root;
	while(p||!StackEmpty(S)){
		if(p){//當p不為空 
			printf("%c",p->data); 
			//入棧 
			push(S,p);
			p = p->Left;
		}else{//當p為空 
			p = S->num[S->top];
			pop(S,p);
			p = p->Right;
			//訪問右節點		 
		}
	}
}

中序非遞迴遍歷一個二叉樹

void InOrder(BiTree root){
	SeqStack* S = (SeqStack*)malloc(sizeof(SeqStack));
	InitStack(S);
	BiTNode* p;
	p = root;
	while(p||!StackEmpty(S)){
		if(p){//當p不為空
			//入棧
			push(S,p);
			p = p->Left;
		}else{//當p為空 
			p = S->num[S->top];
			pop(S,p);
			printf("%c",p->data); 
			p = p->Right;
			//訪問右節點		 
		}
	}
}

後序非遞迴遍歷一個二叉樹

void PostOrder(BiTNode *root)
{
    SeqStack *S = (SeqStack *)malloc(sizeof(SeqStack));
	S->top = -1 ;
    BiTNode *p,*q;
    p = root;
    q = NULL;
    while(p||S->top!=-1) {
        if(p){ 
            push(S,p);
            p = p->Left;
        }
		else{
			p = S->num[S->top];
			if(p->Right==NULL || p->Right == q){
				printf("%c",p->data);
				S->top--;
				q = p;
				p = NULL; 
			}else{
				p = p->Right;
			}
		}
    }
}

層次遍歷

void LevelOrder(BiTree root){
	SqQueue *Q = (SqQueue*)malloc(sizeof(SqQueue));
	BiTree p = (BiTree)malloc(sizeof(BiTNode));
	Q->front = -1;
	Q->rear = -1;
	Q->rear++; 
	Q->num[Q->rear] = root;
	while(Q->rear-Q->front!=0){
		Q->front++;
		p = Q->num[Q->front];
		printf("%c",p->data);
		if(p->Left!=NULL){
			Q->rear++;
			Q->num[Q->rear] = p->Left;
		} 
		if(p->Right!=NULL){
			Q->rear++;
			Q->num[Q->rear] = p->Right;
		}
	}
} 

葉子結點個數/度為0的結點個數

int leaveSum(BiTree root){
	int leaveCount;
	if(root==NULL){
		leaveCount = 0;          	
	}else if((root->Left==NULL&&root->Right==NULL)){
		leaveCount = 1;	
	}else{
		leaveCount = leave(root->Left)+leave(root->Right);
	}
	return leaveCount;
}

度為1的節點個數

int leaveOne(BiTree root){
	int leaveCount;
	if(root!=NULL){
		if((root->Left!=NULL&&root->Right==NULL)||(root->Left==NULL&&root->Right!=NULL)){
			leaveCount = 1;
		}else{
			leaveCount = 0;
		}
		return leaveCount+leaveOne(root->Left)+leaveOne(root->Right);	
	}
	return 0;
}

度為2的節點個數

int leaveTwo(BiTree root){
	int leaveCount;
	if(root!=NULL){
		if(root->Left!=NULL&&root->Right!=NULL){
			leaveCount = 1;
		}
		else{
			leaveCount = 0;
		}
		return leaveCount+leaveTwo(root->Left)+leaveTwo(root->Right);	
	}
}