#include <stdio.h>
#include <stdlib.h>

typedef struct Node
{
 char data;
 struct Node *LeftChild;
 struct Node *RightChild;
 struct Node *next;
}Node;

Node *RootNode;
Node *topp;

int currentNodeCount = 0;

void push(Node *node)
{
 if(currentNodeCount == 0)
 {
  topp = (Node *)malloc(sizeof(Node));
  topp = node;
  topp->next = NULL;
  currentNodeCount++;
 }
 else
 {
  node->next = topp;
  topp = node;
  currentNodeCount++;
 }
}

Node *pop()
{
 Node *temp;
 if(currentNodeCount != 0)
 {
  temp = topp;
  printf("%c ", topp->data);
  topp = topp->next;
  currentNodeCount--;
  temp->next = NULL;
  return temp;
 }
}

void insertLeftChild(Node *New, Node *Parent)
{
 Parent->LeftChild = New;
 New->LeftChild = NULL;
 New->RightChild = NULL;
}

void insertRightChild(Node *New, Node *Parent)
{
 Parent->RightChild = New;
 New->LeftChild = NULL;
 New->RightChild = NULL;
}

Node* GetLeftChild(Node *Parent)
{
  if(Parent->LeftChild != NULL)
  {
   return Parent->LeftChild;
  }
  else
  {
   return NULL;
  }
}

Node* GetRightChild(Node *Parent)
{
 if(Parent->RightChild != NULL)
 {
  return Parent->RightChild;
 }
 else
 {
  return NULL;
 }
}

void deleteNode(Node *Parent)
{
 if(Parent != NULL)
 {
  deleteNode(Parent->LeftChild);
  deleteNode(Parent->RightChild);
  free(Parent);
 }
}

void deleteTree()
{
 deleteNode(RootNode);
}

void posttravel(Node *parent)
{
 static int count = 0;
 if(count == 0)
 {
  count++;
  posttravel(RootNode);
 }
 else
 {
  if(parent != NULL)
  {
  printf("%c ", parent->data);
  posttravel(parent->LeftChild);
  posttravel(parent->RightChild);
  }
 }
}

void midtravel(Node *parent)
{
 static int count = 0;
 if(count == 0)
 {
  count++;
  midtravel(RootNode);
 }
 else
 {
  if(parent != NULL)
  {
   midtravel(parent->LeftChild);
   printf("%c ", parent->data);
   midtravel(parent->RightChild);
  }
 }
}

void finaltravel(Node *parent)
{
 static int count = 0;
 if(count == 0)
 {
  count++;
  finaltravel(RootNode);
 }
 else
 {
  if(parent != NULL)
  {
   finaltravel(parent->LeftChild);
   finaltravel(parent->RightChild);
   printf("%c ", parent->data);
  }
 }
}
void main()
{
 Node *B, *C, *D, *E, *F, *G;
 Node *parent;
 Node *LeftChild;
 Node *RightChild;
 Node *Now;

 topp = (Node *)malloc(sizeof(Node));
 topp->next = NULL;
 RootNode = (Node *)malloc(sizeof(Node));
 RootNode->data = 'A';
 RootNode->LeftChild = NULL;
 RootNode->RightChild = NULL;
 

 B = (Node *)malloc(sizeof(Node));
 C = (Node *)malloc(sizeof(Node));
 D = (Node *)malloc(sizeof(Node));
 E = (Node *)malloc(sizeof(Node));
 F = (Node *)malloc(sizeof(Node));
 G = (Node *)malloc(sizeof(Node));
 B->data = 'B';
 C->data = 'C';
 D->data = 'D';
 E->data = 'E';
 F->data = 'F';
 G->data = 'G';
 
 insertLeftChild(B, RootNode);
 insertRightChild(C, RootNode);
 insertLeftChild(D, B);
 insertRightChild(E, B);
 insertLeftChild(F, C);
 insertRightChild(G, C);

 posttravel(RootNode);
 printf("\n");
 midtravel(RootNode);
 printf("\n");
 finaltravel(RootNode);
 printf("\n");

 push(RootNode);
 parent = RootNode;
 //여기부터
 while(1)
 {
  if(currentNodeCount == 0)
   break;
  else
  {
   Now = pop();
   
   if(RootNode->LeftChild != NULL)
    LeftChild = GetLeftChild(RootNode);
   if(RootNode->RightChild != NULL)
    RightChild = GetRightChild(RootNode);
   if(LeftChild != NULL)
   {
    push(RightChild);
   }
   if(RightChild != NULL)
   {
    push(LeftChild);
   }
  }
  free(Now);
 }
}
 
아마도 //여기부터 라고 쓴 부분에 잘못된 게 있는 것 같은데.......
재귀호출을 통한 순회는 잘 되거든요. 에휴 어디가 문젠지... 구원좀 부탁할게요 ㅠㅠ