数据结构复习——二叉树的几个基本操作

包括了几个很基本的操作，树的创建删除遍历等等

#include<bits/stdc++.h>
using namespace std;
typedef struct node* tree_pointer;
struct node
{
    char ch;
    tree_pointer left_child,right_child;
};

tree_pointer create(tree_pointer T)
{
    char ch;
    cin>>ch;
    if(ch=='.')
        T=NULL;
    else
    {
        T=new node;
        T->ch=ch;
        T->left_child=create(T->left_child);
        T->right_child=create(T->right_child);
    }
    return T;
}
void destroy(tree_pointer T)
{
    if(T)
    {
        destroy(T->left_child);
        destroy(T->right_child);
        delete T;
        T=NULL;
    }
}
void preorder(tree_pointer T)
{
    if(T)
    {
        cout<<T->ch;
        preorder(T->left_child);
        preorder(T->right_child);
    }
}
void inorder(tree_pointer T)
{
    if(T)
    {
        inorder(T->left_child);
        cout<<T->ch;
        inorder(T->right_child);
    }
}
void postorder(tree_pointer T)
{
    if(T)
    {
        preorder(T->left_child);
        preorder(T->right_child);
        cout<<T->ch;
    }
}
queue <tree_pointer> q;
void levelorder(tree_pointer T)
{
    if(T)
    {
        q.push(T);
        while(!q.empty())
        {
            tree_pointer temp;
            temp=q.front();
            q.pop();
            cout<<temp->ch;
            if(temp->left_child)
                q.push(temp->left_child);
            if(temp->right_child)
                q.push(temp->right_child);
        }
    }
}
int leaf(tree_pointer T)
{
    if(!T)
        return 0;
    else
    {
        if(!T->left_child&&!T->right_child)
            return 1;
        return leaf(T->left_child)+leaf(T->right_child);
    }
}
int height(tree_pointer T)
{
    if(!T)
        return 0;
    return 1+max(height(T->left_child),height(T->right_child));
}
void exchangechild(tree_pointer T)
{
    if(T)
    {
        tree_pointer temp;
        if(T->left_child||T->right_child)
        {
            temp=T->left_child;
            T->left_child=T->right_child;
            T->right_child=temp;
            exchangechild(T->left_child);
            exchangechild(T->right_child);
        }
    }
}


int main()
{
    tree_pointer T;
    T=create(T);
    preorder(T);
    cout<<endl;
    inorder(T);
    cout<<endl;
    postorder(T);
    cout<<endl;
    levelorder(T);
    cout<<endl;
    return 0;
}