数据结构 二叉树及中序、先序和后序输出

        当初写个论坛分页，对二叉树感到很新奇，简单分页的话都不难，可谓一种神奇的结构，事实上搜索引擎也是大的树吧。

         其中水平的顺序输入树后，找到相对应的节点的位置的算法相当微妙。二叉树中0代表空，按-1结束输入。可以进行中序，先序和后序输出。

         还是分为  tree.h  ,tree .c , main.c

          tree.h

#include<stdio.h>
#include<malloc.h>
#define  MAX 100
typedef int DataType;
typedef struct BinTree *PNode;
struct BinTree{
	DataType info;
	PNode llink;
	PNode rlink;
};
typedef struct BinTree *PTree;

PTree createTree();
void levelorder(PTree ptree);
int isEmptyTree(PTree ptree);
PTree initTree(PTree ptree,DataType *data,int number);
PNode rootOfTree(PTree ptree);
PNode llinkTree(PTree ptree); 
PNode rlinkTree(PTree ptree);
void visit(PNode pnode);
PNode parentTree(PTree ptree,PNode pnode);
void inorder(PTree ptree); 
void preorder(PTree ptree);
void backorder(PTree ptree);
int depth(PTree ptree);
int leafNumber(PTree ptree);

tree .c

#include "tree.h"
int main(){
	int data[100];
	int n = 0;
	PTree ptree = createTree();
	printf("Please input the data of tree in level order(ending with -1:\n");
	while(1){
		scanf("%d",&data[n]);
		if(data[n] == -1) break;
		n++;
	}
	//printf("%d",n);
	// 自己发毛了  init只是return tree 我竟然没有把原始的ptree 赋值进去！ 
	ptree = initTree(ptree,data,n);
	printf("the depth is %d \n",depth(ptree));
	printf(" the leafnumber is %d\n",leafNumber(ptree));
//	levelorder(ptree);
	//visit(ptree);
	printf("\n");
	printf("the level order is : \n");
	levelorder(ptree);
	printf("the in order is : \n");
	inorder(ptree);
}

main.c

#include "tree.h"
#include<malloc.h>
PTree createTree(){
	PTree ptree = (PTree)malloc(sizeof(struct BinTree));
	if(ptree == NULL) printf("create fail");
	ptree ->llink = NULL;
	ptree ->rlink = NULL;	
	return ptree;
}

void levelorder(PTree ptree){
	int i,j;
	PNode pnode[MAX] = {NULL};
	pnode[0] = ptree;
	i = 0; j = 1; 
	while(j>i){
		PNode temp = pnode[i];
		if(temp != NULL){
			if(temp ->llink != NULL) pnode[j++] = temp ->llink;
			if(temp ->rlink != NULL) pnode[j++] = temp ->rlink;	
			printf("%d\n",temp->info);
		}
		i++;			 
	} 
	printf("\n");
}

int isEmptyTree(PTree ptree){
	return (ptree ->llink==NULL&&ptree ->rlink==NULL);
}

PTree initTree(PTree ptree,DataType *data,int number){
	int i;
	PNode temp;
	PNode pnode[MAX] ={NULL}; 
	for(i = 0; i<number ; i++){
	//the 0 represent the node  NULL		
		if(data[i] != 0) 
		// 尝试不分配空间 直接用数组的pnode 直接赋值 
		//不行  只是数组而已  里面的空间没有分配出来 
			temp = (PNode)malloc(sizeof(struct BinTree));
			temp ->llink = NULL;
			temp ->rlink = NULL;
			temp ->info = data[i]; 	
			pnode[i] = temp;	
		//	printf("%d \n",pnode[i]->info);			
	}
	
	for(i = 0; i<number ; i++){	
		if(pnode[i] != NULL && i*2+1 < MAX) 
		pnode[i] ->llink = pnode[i*2+1];	
	}
	
	for(i = 0; i<number ; i++){	
		if(pnode[i] != NULL && i*2+2 < MAX) 
		pnode[i] ->rlink = pnode[i*2+2];	
	}

	ptree = pnode[0];
	return ptree;
}

PNode rootOfTree(PTree ptree){
	PNode p ;
	if(ptree == NULL) printf("the root does not exist");
	 p = ptree;
	return p;
} 

PNode llinkTree(PTree ptree){
	if(ptree == NULL) printf("the llink does not exist");
		return NULL;
	
	return ptree->llink;
}

PNode rlinkTree(PTree ptree){
    if(ptree == NULL) printf("the rlink does not exist");
	
	return ptree->rlink;
}

void visit(PNode pnode){
	if(pnode == NULL) printf("it is null");
	printf("%d",pnode->info);
}

PNode parentTree(PTree ptree,PNode pnode){
	PNode temp = NULL;
	if(ptree == NULL){
		printf("it is null");
		return NULL;
	}
	else if(pnode = ptree){
		printf("it is null");
		return NULL;
	}
	else if(ptree ->llink == pnode || ptree ->rlink == pnode)
		return ptree;
	if(ptree != NULL && temp == NULL) temp = parentTree(ptree->llink,pnode);
	if(ptree != NULL && temp == NULL) temp = parentTree(ptree->rlink,pnode);
	
	return temp;
}

void inorder(PTree ptree){
	if(ptree == NULL) return;
	inorder(ptree ->llink);
	visit(rootOfTree(ptree));
	inorder(ptree ->rlink);	
}

void preorder(PTree ptree){
    if(ptree == NULL) return;
    visit(rootOfTree(ptree));
    preorder(ptree ->llink);
	preorder(ptree ->rlink);
	
}

void backorder(PTree ptree){
	if(ptree == NULL) return; 
    backorder(ptree ->llink);
	backorder(ptree ->rlink);
    visit(rootOfTree(ptree));
}

int depth(PTree ptree){
	int i = 0,j = 0;
//	if(ptree != NULL )
//		return 1;
	if(ptree == NULL) return 0;
	if(ptree != NULL){
		i = depth(ptree ->llink);
		j = depth(ptree ->rlink);
	}
	return i>j?i+1:j+1;
}

int leafNumber(PTree ptree){
	int i = 0;
	if(ptree != NULL && ptree ->llink == NULL && ptree ->rlink == NULL){
	//	printf("%d",ptree ->info);
		return 1;
	}
	if(ptree == NULL) return 0;
	if(ptree != NULL){
		i = leafNumber(ptree ->llink)+leafNumber(ptree ->rlink);
	}
	return i;
}

        这些基础的东西，看到了指针的用处，真的很灵活，自由度高，对于一些人来讲，确实是王道。