二叉树的基本运算

#include<stdio.h>#include<stdlib.h>//二叉树结点定义typedef struct BT{    char data;    struct BT *lchild;    struct BT *rchild;}BT;//建立二叉树（前序创建）BT *createtree(){    BT *bt;    char x;    scanf("%c",&x);    if (x == '0')        bt = NULL;    else    {        bt = (BT *)malloc(sizeof(BT));        bt->data = x;        bt->lchild = createtree();        bt->rchild = createtree();    }    return (bt);}//前序递归遍历void  Preorder(BT *bt){    if (bt != NULL)    {        printf("%c ",bt->data);        Preorder(bt->lchild);        Preorder(bt->rchild);    }}int count = 0;//统计二叉树叶子结点数void leafnum(BT *bt)   //开始时,bt指向根结点,count（初值为0）作为全局变量用来统计个数{    if (bt)         //判断bt是否为空    {        if (bt->lchild == NULL && bt->rchild == NULL)        {            count++;        }        leafnum(bt->lchild);    //递归遍历左子树        leafnum(bt->rchild);    //递归遍历右子树    }}//统计二叉树结点个数void Nodenum(BT *bt){    if (bt)    {        count++;        //count（初值为0）为全局变量        Nodenum(bt->lchild);    //递归遍历左子树        Nodenum(bt->rchild);    //递归遍历右子树    }}//求二叉树的深度int treedepth(BT *bt){    int ldepth, rdepth;    if (bt == NULL)        return 0;    else    {        ldepth = treedepth(bt->lchild);        rdepth = treedepth(bt->rchild);        if (ldepth > rdepth)            return (ldepth + 1);        else            return (rdepth + 1);    }}//查找数据元素BT *search(BT *bt, char x)   //查找数据x{    if (bt->data == x)       //当查找成功时返回该结点的指针        return bt;    //否则，在左右子树分别查找    if (bt->lchild != NULL)        return (search(bt->lchild, x));    if (bt->rchild != NULL)        return (search(bt->rchild, x));    return NULL;     //查找失败，返回空指针}