(C语言)二叉树层次遍历(数据结构十六)

1.数据类型定义

在代码中为了清楚的表示一些错误和函数运行状态，我们预先定义一些变量来表示这些状态。在head.h头文件中有如下定义：

//定义数据结构中要用到的一些变量和类型#ifndef HEAD_H#define HEAD_H#include <stdio.h>#include <malloc.h>#include <stdlib.h>#include <math.h>#define TRUE  1#define FALSE 0#define OK    1#define ERROR  0#define INFEASIBLE -1#define OVERFLOW   -2    //分配内存出错typedef int  Status;     //函数返回值类型typedef int  ElemType;   //用户定义的数据类型#endif

2.层次遍历中我们需要用到队列,定义队列头文件如下LinkQueue.h中代码:

#ifndef LINKQUEUE_H#define LINKQUEUE_H#include "head.h"#include "BiTree.h"//队列中数据类型为树节点typedef pBiNode Type;//队列节点typedef struct Node{Type data;struct Node* next;}Node,*pNode;                //队列typedef struct LinkQueue{pNode head;pNode tail;int  length;}LinkQueue,*pLinkQueue;//初始化队列Status InitQueue(pLinkQueue &Q){Q=(pLinkQueue)malloc(sizeof(LinkQueue));if(!Q) return OVERFLOW;pNode p=(pNode)malloc(sizeof(Node));if(!p) return OVERFLOW;p->next=NULL;Q->head=p;Q->tail=p;Q->length=0;return OK;}//队列长度Status QueueLength(pLinkQueue Q){if(Q==NULL) return ERROR;return Q->length;}//队列是否为空Status QueueEmpty(pLinkQueue Q){return QueueLength(Q)==0;}//从队尾插入数据Status InsertQueue(pLinkQueue &Q,Type e){pNode q=Q->tail;pNode p=(pNode)malloc(sizeof(Node));p->data=e;p->next=NULL;Q->tail=p;q->next=Q->tail;Q->length++;return true;}//从队头删除数据Status DeleteQueue(pLinkQueue &Q,Type &e){if(QueueLength(Q)<1) return ERROR;pNode p=Q->head;Q->head=p->next;e=Q->head->data;free(p);Q->length--;return true;}#endif

3.二叉树头文件 BiTree.h代码如下:

#ifndef BITREE_H#define BITREE_H#include "head.h"typedef struct BiNode{ElemType data;struct BiNode *left,*right;}BiNode,*pBiNode;Status InsertRight(pBiNode &root,ElemType e);Status InsertLeft(pBiNode &root,ElemType e);Status InitBiTree(pBiNode &tree){tree=(pBiNode)malloc(sizeof(BiNode));if(!tree) return OVERFLOW;tree->data=-999999;tree->left=NULL;tree->right=NULL;return OK;}Status BiTreeEmpty(pBiNode root){if(root==NULL) return ERROR;return root->left==root->right && root->data==-999999;}Status HasNoNode(pBiNode root){if(root==NULL) return ERROR;return root->left==root->right ;}Status CreatTreeNode(pBiNode &node,ElemType e){node=(pBiNode)malloc(sizeof(BiNode));if(!node) return OVERFLOW;node->data=e;node->left=NULL;node->right=NULL;return OK;}Status InsertRight(pBiNode &root,ElemType e){if(root->right==NULL){if(e>root->data){pBiNode p;CreatTreeNode(p,e);root->right=p;return OK;}else{pBiNode p;CreatTreeNode(p,e);root->left=p;return OK;}}else{e>root->data? InsertRight(root->right,e):InsertLeft(root,e);}}Status InsertLeft(pBiNode &root,ElemType e){if(root->left==NULL){if(e>root->data){pBiNode p;CreatTreeNode(p,e);root->right=p;return OK;}else{pBiNode p;CreatTreeNode(p,e);root->left=p;return OK;}}else{e<=root->data?InsertLeft(root->left,e):InsertRight(root,e);}}Status InsertTree(pBiNode &root,ElemType e){if(BiTreeEmpty(root)){root->data=e;return true;}if(e>root->data){InsertRight(root,e);}else{InsertLeft(root,e);}}Status CreateBiTree(pBiNode &root,ElemType *a,int n){for (int i=0;i<n;i++){InsertTree(root,a[i]);}return true;} Status print(ElemType e ){ printf("%d ",e); return true; }Status PreOrderTraverse(pBiNode root,Status(*p)(int)){if(root){(*p)(root->data);PreOrderTraverse(root->left,p);PreOrderTraverse(root->right,p);}return OK;}Status MiddleOrderTraverse(pBiNode root,Status(*p)(int)){if(root){MiddleOrderTraverse(root->left,p);(*p)(root->data);MiddleOrderTraverse(root->right,p);}return OK;}Status AfterOrderTraverse(pBiNode root,Status(*p)(int)){if(root){AfterOrderTraverse(root->left,p);AfterOrderTraverse(root->right,p);(*p)(root->data);}return OK;}Status ClearBiTree(pBiNode &root){if(root){ClearBiTree(root->left);ClearBiTree(root->right);free(root);root==NULL;}return OK;}#endif

4.层次遍历二叉树测试代码:

#include "BiTree.h"#include "LinkQueue.h"//层次遍历二叉树void LevelOrder(pBiNode root){pLinkQueue Q;      InitQueue(Q);  InsertQueue(Q,root);while (!QueueEmpty(Q)){pBiNode e;DeleteQueue(Q,e);printf("%d ",e->data);if (e->left){InsertQueue(Q,e->left);}if (e->right){InsertQueue(Q,e->right);}}}void main(){ElemType a[14]={100,50,200,40,30,45,60,55,61,200,150,300,250,400};pBiNode root;InitBiTree(root);CreateBiTree(root,a,14);printf("前序：");PreOrderTraverse(root,print);printf("\n中序：");MiddleOrderTraverse(root,print);printf("\n后序：");AfterOrderTraverse(root,print);printf("\n层次遍历：");LevelOrder(root);printf("\n");ClearBiTree(root);}

5.插入的二叉树为:

6.层次遍历结果

前序：100 50 40 30 45 60 55 61 200 150 300 250 400中序：30 40 45 50 55 60 61 100 150 200 250 300 400后序：30 45 40 55 61 60 50 150 250 400 300 200 100层次遍历：100 50 200 40 60 150 300 30 45 55 61 250 400