二叉树的建立（广义表）及3种遍历

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/*****************************************************
Copyright (C)
FileName: BiTree.c
Author: Luqing             Date:2006/4/11
Description:     // The basic operations of Bi_Tree
Version:         // v1.0
Function List:   // creatree, preorder, inorder, postorder
******************************************************/
#include <stdio.h>
#include <stdlib.h>
#define MaxSize 100
typedef char ElemType;
typedef struct node
{
ElemType data;
struct node *left,*right;
} BiTreeNode,*BiTree;

struct node * creatree(char *str)
{
BiTreeNode *stack[MaxSize],*p;
BiTreeNode *BT;
int top=-1,k,j=0;//top为栈指针,k指定是左还是右孩子,j为str指针
char ch;
BT=NULL;
ch=str[j];
while (ch!='/0')
{
  switch(ch)
  {
  case '(':top++;stack[top]=p;k=1; //为左结点
   break;
  case ')':top--;
   break;
  case ',':k=2;   //为右结点
   break;
  default: p=(BiTreeNode *)malloc(sizeof(BiTreeNode));
   p->data=ch;p->left=p->right=NULL;
   if (BT==NULL) //根结点//
    BT=p;
   else
   {
    switch(k)
    {
    case 1:stack[top]->left=p;
     break;
    case 2:stack[top]->right=p;
    }
   }
  }
  j++;
  ch=str[j];
}
return BT;
}
void preorder(BiTreeNode *BT)
{
if (BT!=NULL)
{
  printf("%c",BT->data);
  preorder(BT->left);
  preorder(BT->right);
}
}
void inorder(BiTreeNode *BT)
{
if (BT!=NULL)
{
  inorder(BT->left);
  printf("%c",BT->data);
  inorder(BT->right);
}
}
void postorder(BiTreeNode *BT)
{
if (BT!=NULL)
{
  postorder(BT->left);
  postorder(BT->right);
  printf("%c",BT->data);
}
}

int main()
{
BiTreeNode *B;
//char *s="A(B,C)";
char *s="A(B(E,F),C(D(G,),)";
B=creatree(s);
printf("/n前序遍历:");
preorder(B);
printf("/n中序遍历:");
inorder(B);
printf("/n后序遍历:");
postorder(B);
printf("/n");

return 0;
}