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.树的头文件 BiTree.h代码如下:
#ifndef BITREE_H
#define BITREE_H#include "head.h"//Link为指针 Thread为线索
typedef enum PointerTag {Link,Thread};typedef struct BiNode{ElemType data;struct BiNode *left,*right;int LTag,RTag; //左右标志
}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
3.线索二叉树代码
#include "BiTree.h"//中序线索
void InOrder( pBiNode root,pBiNode &pre){if (root!=NULL){InOrder(root->left,pre);if (root->left==NULL){root->left=pre;root->LTag=1;}if (pre!=NULL && pre->right==NULL){pre->right=root;pre->RTag=1;}pre=root;InOrder(root->right,pre);}
}
//线索
void CreateInOrder(pBiNode& root){pBiNode pre=NULL;if(root!=NULL){InOrder(root,pre);pre->right=NULL;pre->RTag=1;}
}//获取头指针
pBiNode FirstNode(pBiNode root){while (root->LTag!=1){root=root->left;}return root;
}
//获取下一个节点
pBiNode NextNode(pBiNode root){if (root->RTag!=1){return FirstNode(root->right);}else{return root->right;}
}
//遍历线索
void InOrder(pBiNode root){for (pBiNode p=FirstNode(root);p!=NULL;p=NextNode(p)){printf("%d ",p->data);}
}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);CreateInOrder(root);printf("\n线索二叉树中序:");InOrder(root);printf("\n");ClearBiTree(root);}
4.测试结果
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
线索二叉树中序:30 40 45 50 55 60 61 100 150 200 250 300 400