自己用C写的数据结构中

#include <stdio.h>
#include <math.h>
#define NULL 0
typedef int elementtype;
typedef struct node{
 elementtype data;
 struct node *Lchild,*Rchild;
}tree;

/* workout the tree's high */
int high(tree *t)
{
 if(t==NULL) return 0;
 else
     return (max(high(t->Lchild),high(t->Rchild))+1);
}

/* max length of Lchild & Rchild */
int max(int x,int y)
{
 if(x>y) return x;
 else return y;
}

/* create a Betree */
create(tree *t,int NodeNum)
{
 elementtype x;
 int i,layer;
 layer=log(NodeNum)/log(2)+1;
 printf("\nInput data for Node %d in layer %d :",NodeNum,layer);
 scanf("%d",&x);
 t->data=x;
 printf("create lchild for Node %d in layer %d (0 for No)?",NodeNum,layer);
 scanf("%d",&i);
 if(i==0) t->Lchild=NULL;
 else
    {
     t->Lchild=(tree *)malloc(sizeof(tree));
     create(t->Lchild,2*NodeNum);
    }
 printf("create rchild for Node %d in layer %d (0 for No)?",NodeNum,layer);
 scanf("%d",&i);
 if(i==0) t->Rchild=NULL;
 else
    {
     t->Rchild=(tree *)malloc(sizeof(tree));
     create(t->Rchild,2*NodeNum+1);
    }
 return 0;
}

/* preorder */
void preorder(tree *t)
{
 if(t!=NULL)
   {
    printf("%d ",t->data);
    preorder(t->Lchild);
    preorder(t->Rchild);
   }
}

/* midorder */
void midorder(tree *t)
{
 if(t!=NULL)
   {
    midorder(t->Lchild);
    printf("%d ",t->data);
    midorder(t->Rchild);
   }
}

/* postorder */
void postorder(tree *t)
{
 if(t!=NULL)
   {
    postorder(t->Lchild);
    postorder(t->Rchild);
    printf("%d ",t->data);
   }
}

/* countleaf */
int countleaf(tree *t)
{
 if(t==NULL)
    return 0;
 if(t->Lchild==NULL&&t->Rchild==NULL)
    return 1;
 return(countleaf(t->Lchild)+countleaf(t->Rchild));
}

/* nodes */
int nodes(tree *t)
{
 if(t==NULL)
   return 0;
 else
    return(nodes(t->Lchild)+nodes(t->Rchild)+1);
}

void main()
{
 tree *t;
 t=(tree *)malloc(sizeof(tree));
 create(t,1);
 printf("\nThe Betree's high is:");
 printf(" %d\n",high(t));
 printf("\nPRESS ANY KEY TO CONTINUE will get preorder midorder postorder.");
 getch();
 printf("\npreorder: ");
 preorder(t);
 printf("\nmidorder: ");
 midorder(t);
 printf("\npostorder: ");
 postorder(t);
 getch();
 printf("\nThe leaf's number is: %d",countleaf(t));
 printf("\nThe total nodes' number is: %d",nodes(t));
 getch();
}