设计要求：对于任何一个给定的树或二元树依据其层次关系从上到下（层次之间），从左到右（同一层内）进行遍历。（可以通过一个书籍的目录来体现，即建立一个图书树形目录的建立、图书目录的显示、以及图书目录的检索

#include <stdio.h> #include <stdlib.h> #define Maxsize 20

typedef char ElemType; struct Bitree { ElemType data; struct Bitree *l; struct Bitree *r; }; typedef struct Bitree TreeNode; typedef struct Bitree *BiTree; void LevelOrder(BiTree root) { BiTree ptr[Maxsize]; int rear = -1; int front = -1; if(root==NULL) return; else { rear = rear + 1; ptr[rear] = root; while(front!=rear) { front = front + 1; printf("%c\n",ptr[front]->data); if( ( ptr[front]->l ) != NULL ) { if( rear < (Maxsize-1)) { rear = rear + 1; ptr[rear] = ptr[front]->l; } else { printf("The queue is full\n"); } } if( ( ptr[front]->r ) != NULL ) { if( rear < (Maxsize-1)) { rear = rear + 1; ptr[rear] = ptr[front]->r; } else { printf("The queue is full\n"); } } } } }

BiTree CreateBiTree()//按先序次序输入二叉树中结点的值，'#'代表空树 { char e; BiTree tmp = NULL;

if( (e=getchar())!='#' ) { getchar();//接收回车符 tmp=(BiTree)malloc(sizeof(TreeNode)); if(!tmp) return NULL; tmp->data=e; printf("请输入左孩子："); tmp->l=CreateBiTree(); printf("请输入右孩子："); tmp->r=CreateBiTree(); } else getchar();//接收回车符

return tmp; }

void LevelOrder(BiTree root); BiTree CreateBiTree();

void main() { BiTree root = NULL; root = CreateBiTree(); LevelOrder(root); }