二叉树的生成和遍历

#include<iostream>using namespace std;typedef struct node *tree_pointer;struct node{ char ch; tree_pointer left_child,right_child;};tree_pointer root=NULL;tree_pointer create(tree_pointer ptr){  char ch; scanf("%c",&ch); if(ch==' ')  ptr=NULL; else{  ptr=(tree_pointer)malloc(sizeof(node));     ptr->ch=ch;     ptr->left_child=create(ptr->left_child);      ptr->right_child=create(ptr->right_child); } return ptr;} void preorder(tree_pointer ptr){ if(ptr){  printf("%c",ptr->ch);  preorder(ptr->left_child);  preorder(ptr->right_child); }}void inorder(tree_pointer ptr){ if(ptr){  inorder(ptr->left_child);  printf("%c",ptr->ch);  inorder(ptr->right_child); }}int leaf(tree_pointer ptr){ if(!ptr)  return 0; else{  if(!ptr->left_child&&!ptr->right_child)   return 1;  return leaf(ptr->left_child)+leaf(ptr->right_child); }}void main(){ printf("构建一个二叉树：\n"); root=create(root); printf("前序遍历二叉树：\n"); preorder(root); printf("\n"); printf("中序遍历二叉树：\n"); inorder(root); printf("\n"); printf("二叉树的叶子结点个数为%d\n",leaf(root)); system("pause");}