第六章 ------二叉树和树

求先序序列中第K个位置的结点的值

#include <stdio.h>
#include <stdlib.h>
typedef char TElemType;
typedef struct BiTNode
{
    TElemType data;
    struct BiTNode *lchild,*rchild;
}BiTNode ,*BiTree;
void CreateBiTree(BiTree *T)
{
    char data;
    scanf("%c",&data);
    if(data=='#') *T=NULL;
    else
    {
        *T=(BiTree)malloc(sizeof(BiTNode));
        (*T)->data=data;
        CreateBiTree(&((*T)->lchild));
        CreateBiTree(&((*T)->rchild));
    }
}
void printBiTree(BiTree T)
{
    if(T)
    {
        printf("%c",T->data);   
    }
   
}
void Preorder(BiTree T,void (*visit)(BiTree))
{
    if(T)
    {
        visit(T);
        Preorder(T->lchild,visit);
        Preorder(T->rchild,visit);
    }
}
void Preorder2(BiTree T,void (*visit)(BiTree),int *k)
{
    if(T)
    {
        (*k)--;
        if(*k)
        {
            Preorder2(T->lchild,visit,k);
            Preorder2(T->rchild,visit,k);
        }
        else
        {
            visit(T);
        }
    }
   
}
void main()
{
    BiTree T;
    int k;
    void *pt=printBiTree;
    printf("输入二叉树序列：");
    CreateBiTree(&T);
    printf("先序遍历：");
    Preorder(T,pt);
    printf("\n");
    printf("输入要输出的第K个位置：");
    scanf("%d",&k);   
    printf("输出先序序列的第%d个位置的结点的值：",k);
    Preorder2(T,pt,&k);
    printf("\n");
}

---

计算二叉树中叶子结点的数目

#include <stdio.h>
#include <stdlib.h>
typedef char ElemType;
typedef struct TNode 
{
	ElemType data;
	struct TNode *lchild,*rchild;
}TNode,*BiTree;
void createBiTree(BiTree *T)
{
	ElemType data;	
	scanf("%c",&data);
	if(data!='#')
	{
		*T=(TNode *)malloc(sizeof(TNode));
		(*T)->data=data;
		createBiTree(&((*T)->lchild));
		createBiTree(&((*T)->rchild));
	}
	else
	{
		*T=NULL;
	}
}
void Preorder(BiTree T,void (*visit)(BiTree),int *leafnodes )
{
	if(T)
	{
		visit(T);
		if(!T->lchild && !T->rchild) (*leafnodes)++;
		Preorder(T->lchild,visit,leafnodes);
		Preorder(T->rchild,visit,leafnodes);
	}

}
void printBiTree(BiTree T)
{
	if(T)
	{
		printf("%c",T->data);
	}
}
void main()
{
	BiTree T;
	int leafnodes=0;
	void *pt=printBiTree;
	printf("建树：");
	createBiTree(&T);
	printf("先序遍历：");
	Preorder(T,pt,&leafnodes);
	printf("\n");
	printf("叶子结点总数：%d\n",leafnodes);
}