#define MaxSize 1000  typedef char ElemType;  typedef struct node  {      ElemType data;      struct node *lchild;      struct node *rchild;  } BTNode;  //创建二叉树  void CreateBTNode(BTNode *&b,char *str)  {      BTNode *St[MaxSize],*p=NULL;      int top=-1,k,j=0;      char ch;      b=NULL;      ch=str[j];      while(ch!='\0')      {          switch(ch)          {          case '(':top++;St[top]=p;k=1;break;          case ')':top--;break;          case ',':k=2;break;          default:p=(BTNode *)malloc(sizeof(BTNode));              p->data=ch;p->lchild=p->rchild=NULL;              if(b==NULL) b=p;              else              {                  switch(k)                  {                  case 1:St[top]->lchild=p;break;                  case 2:St[top]->rchild=p;break;                  }                 }             }             j++;          ch=str[j];      }     }  //层次遍历算法  void LevelOrder(BTNode *b)  {      BTNode *p;      BTNode *qu[MaxSize];      int front,rear;      front=rear=-1;      rear++;      qu[rear]=b;      while(front != rear)      {          front=(front+1)%MaxSize;          p=qu[front];          printf("%c ",p->data);             if(p->lchild!=NULL)          {              rear=(rear+1)%MaxSize;              qu[rear]=p->lchild;          }             if(p->rchild!=NULL)          {              rear=(rear+1)%MaxSize;              qu[rear]=p->rchild;          }      }  }     //主函数  int main()  {      BTNode *b,*h;      char s[MaxSize] = "A(B(D(,G)),C(E,F))";         CreateBTNode(b,s);      printf("层次遍历算法的访问次序为：");      LevelOrder(b);      printf("\n请输入二叉树括号表示法字符串：\n");      return 0;  }