15. 二叉查找树的镜像

题目： 输入1个二叉查找树，将该树转换为它的镜像，即在转换后的二叉查找树中，左子树的节点都大于右子树的节点，用递归和循环两种方法完成。

二叉查找树中序遍历是从小到大的，镜像树是从大到小的，可用来判断是否转换成功

代码，递归的:

/*
     二叉查找树转换前中序遍历是从小到大，转换后是从大到小
     递归: 若节点有左孩子或者右孩子的话，首先转换左子树，再转换右子树，然后交换节点左右孩子
 */
#include<iostream>
using namespace std;

typedef int datatype;

typedef struct node
{
    datatype value;
    struct node* lchild;
    struct node* rchild;
}Tree;

//先序建树，NULL节点用0表示
Tree* create_tree(void)
{
    int value;
    Tree* t=NULL;

    cin>>value;
    if(value==0)
        return NULL;
    else
    {
        t=new Tree;
        t->value=value;
        t->lchild=create_tree();
        t->rchild=create_tree();
    }
    return t;
}

//释放
void free_tree(Tree* t)
{
    if(t)
    {
        free_tree(t->lchild);
        free_tree(t->rchild);
        delete t;
        t=NULL;
    }
}

Tree* temp=NULL;
void converse(Tree* t)
{
    if(t->lchild || t->rchild)
    {
        converse(t->lchild);
        converse(t->rchild);
        temp=t->lchild;
        t->lchild=t->rchild;
        t->rchild=temp;
    }
}

void inorder(Tree* t)
{
    if(t)
    {
        inorder(t->lchild);
        cout<<t->value<<" ";
        inorder(t->rchild);
    }
}
    
int main(void)
{
    Tree* root;
    root=create_tree();
    cout<<"before..."<<endl;
    inorder(root);
    cout<<endl;
    cout<<"after..."<<endl;
    converse(root);
    inorder(root);
    cout<<endl;
    free_tree(root);
}

 

代码，循环的:

/*
     循环: 应该采用后续遍历，先处理子女，再处理自己
*/

#include<iostream>
using namespace std;


typedef struct node
{
    int value;
    struct node* lchild;
    struct node* rchild;
}Tree;
typedef struct 
{
    Tree* p;
    int count;
}Node;

//栈
#define MAX 100
typedef struct
{
    Node data[MAX];
    int top;
}Stack;

Stack* create_stack(void)
{
        Stack* s=new Stack;
        if(s)
            s->top=-1;
        return s;
}

bool empty_stack(Stack* s)
{
    if(s->top==-1)
        return true;
    return false;
}

bool full_stack(Stack* s)
{
    if(s->top==MAX-1)
        return true;
    return false;
}

void push_stack(Stack* s,Node x)
{
    if(full_stack(s))
        return ;
    ++s->top;
    (s->data[s->top]).p=x.p;
    (s->data[s->top]).count=x.count;
}

void pop_stack(Stack* s,Node* x)
{
    if(empty_stack(s))
        return ;
    x->p=(s->data[s->top]).p;
    x->count=(s->data[s->top]).count;
    --s->top;
}

//先序建树
Tree* create_tree(void)
{
    int value;
    Tree* t=NULL;

    cin>>value;
    if(0==value)
        return NULL;
    else
    {
        t=new Tree;
        t->value=value;
        t->lchild=create_tree();
        t->rchild=create_tree();
    }
    return t;
}

void free_tree(Tree* t)
{
    if(t)
    {
        free_tree(t->lchild);
        free_tree(t->rchild);
        delete t;
        t=NULL;
    }
}

void converse(Tree* t)
{
    Node temp;
    Stack* s;
    Tree* p;
    Tree* temp_point=NULL;

    s=create_stack();
    p=t;

    while(p!=NULL || !empty_stack(s))
    {
        if(p)
        {
            temp.p=p;
            temp.count=0;
            push_stack(s,temp);
            p=p->lchild;
        }
        else
        {
            pop_stack(s,&temp);
            p=temp.p;
            if(temp.count==0)
            {
                temp.count=1;
                temp.p=p;
                push_stack(s,temp);
                p=p->rchild;
            }
            else
            {
                //此时该访问p节点，它的左右孩子都调整完毕了
                temp_point=p->lchild;
                p->lchild=p->rchild;
                p->rchild=temp_point;
                p=NULL;
            }
        }
    }

    delete s;
}

void inorder(Tree* t)
{
    if(t)
    {
        inorder(t->lchild);
        cout<<t->value<<" ";
        inorder(t->rchild);
    }
}

int main(void)
{
    Tree* root;
    root=create_tree();
    cout<<"before..."<<endl;
    inorder(root);
    cout<<endl;
    cout<<"after..."<<endl;
    converse(root);
    inorder(root);
    cout<<endl;

    free_tree(root);

    return 0;
}

先序输入给定的树, 8 6 5 0 0 7 0 0 10 9 0 0 11 0 0