使用C语言构建基本的二叉树数据结构

#include
#include

typedef struct Node{
 int data;
 Node *leftchild;
 Node *rightchild;
}Node;


/*
 初始化一棵二叉树排序树。
*/
void InitBinaryTree(Node**root,int elem)
{
 *root=(Node*)malloc(sizeof(Node));
 if(!(*root))
 {
 printf("Memory allocation for root failed.\n");
 return;
 }
 (*root)->data=elem;
 (*root)->leftchild=NULL;
 (*root)->rightchild=NULL;
}

/*
 向二叉树排序树中插入节点。
*/
void InsertNode(Node *root,int elem)
{
 Node *newnode=NULL;
 Node *p=root,*last_p=NULL;

 newnode=(Node*)malloc(sizeof(Node));
 if(!newnode)
 {
 printf("Memory allocation for newnode failed.\n");
 return;
 }
 newnode->data=elem;
 newnode->leftchild=NULL;
 newnode->rightchild=NULL;

 while(NULL!=p)
 {
 last_p=p;
 if(newnode->datadata)
 {
 p=p->leftchild;
 }
 else if(newnode->data>p->data)
 {
 p=p->rightchild;
 }
 else
 {
 printf("Node to be inserted has existed.\n");
 free(newnode);
 return;
 }
 }
 p=last_p;
 if(newnode->datadata)
 {
 p->leftchild=newnode;
 }
 else
 {
 p->rightchild=newnode;
 }
}

/*
 创建一棵二叉树排序树。
*/
void CreatBinarySearchTree(Node **root,int data[],int num)
{
 int i;

 for(i=0;i
 {
 if(NULL==*root)
 {
 InitBinaryTree(root,data[i]);
 }
 else
 {
 InsertNode(*root,data[i]);
 }
 }
}

 bt rebuildTree(char *pre, char *in, int len); 

 /** 
  * Description:根据前序和中序构建二叉树 
  */ 
 bt rebuildTree(char *pre, char *in, int len) 
 { 
  bt t; 
  if(len <= 0) 
  { 
   //递归终止 
   t = NULL; 
  }else 
  { 
   //递归主体 
   int index = 0; 
    
   while(index < len && *(pre) != *(in + index)) 
   { 
    index ++; 
   } 
    
   if(index >= len) 
   { 
    printf("前序遍历或者中序遍历数组有问题!\n"); 
    exit(-1); 
   } 
    
   t = (struct bintree *)malloc(sizeof(struct bintree)); 
   t->item = *pre; 
   t->lchild = rebuildTree(pre + 1, in, index); 
   t->rchild = rebuildTree(pre + (index + 1), in + (index + 1), len - (index + 1)); 
  } 
  return t; 
 } 

 /** 
  * 中序、后序序列构建二叉树 
  */ 
 btree* rebuildTree(char *order, char *post, int len); 

 /** 
  * 根据中序和后序序列构建二叉树 
  * (ps:昨晚参加阿里笔试，等到最后说可以免笔试直接面试，今天估计还是要根据学校筛选，哈哈，为了这点 
  * 也得参加阿里笔试，不能让自己的学校受到鄙视) 
  */ 
  
 #include <stdio.h> 
 #include <stdlib.h> 
 #include <string.h> 
  
 int n; 
  
 typedef struct btree { 
  struct btree *lchild; 
  struct btree *rchild; 
  char data; 
 } btree; 
  
 /** 
  * 中序、后序序列构建二叉树 
  */ 
 btree* rebuildTree(char *order, char *post, int len) 
 { 
  btree *t; 
  
  if (len <= 0) { 
   return NULL; 
  } else { 
   int index = 0; 
  
   while (index < len && *(post + len - 1) != *(order + index)) { 
    index ++; 
   }  
  
   t = (btree *)malloc(sizeof(btree)); 
   t->data = *(order + index); 
   t->lchild = rebuildTree(order, post, index); 
   t->rchild = rebuildTree(order + index + 1, post + index, len - (index + 1)); 
  } 
  
  return t; 
 } 
  
 /** 
  * 前序遍历二叉树 
  */ 
 void preTraverse(btree *t) 
 { 
  if (t) { 
   printf("%c ", t->data); 
   preTraverse(t->lchild); 
   preTraverse(t->rchild); 
  } 
 } 
  
 int main(void) 
 { 
  int i; 
  char *post, *order; 
  btree *t; 
  
  while (scanf("%d", &n) != EOF) { 
   post = (char *)malloc(n); 
   order = (char *)malloc(n); 
    
   getchar(); 
   for (i = 0; i < n; i ++) 
    scanf("%c", order + i); 
  
   getchar(); 
   for (i = 0; i < n; i ++) 
    scanf("%c", post + i); 
  
   t = rebuildTree(order, post, n); 
  
   preTraverse(t); 
   printf("\n"); 
  
   free(post); 
   free(order); 
  
  } 
  
  return 0; 
 }