麻烦大家帮忙看一个程序~C的 想要知道下这个程序的编程思想 想要详尽的注释~~

#include <stdio.h>
#include <malloc.h>
#define maxsize 1024
#define null 0
struct node
{int data;
struct node *lchild, *rchild;
};
struct node *root;

struct node *CREATREE()
{char ch;
struct node *Q[maxsize];
int front,rear;
struct node *root,*s;
root=null;
front=1;rear=0;
while((ch=getchar())!='#')
{s=null;
if(ch!=' ')
{s=malloc(sizeof(struct node));
s->data=ch;
s->lchild=null;
s->rchild=null;
}
rear++;
Q[rear]=s;
if(rear==1) root=s;
else
{if((s!=null)&&(Q[front]!=null))
if(rear%2==0) Q[front]->lchild=s;
else Q[front]->rchild=s;
if(rear%2==1) front++;
}
}
return root;
}
void preorder(struct node *p)
{if(p!=null)
{printf("%c",p->data);
preorder(p->lchild);
preorder(p->rchild);}