C++之二叉树的创建、查找、四种次序的周游遍历方法以及内存的释放

数据结构的学习心得，还有很多不足之处。。希望看到的大神们能够给出宝贵的修改意见。

以下为运行结果

前序优先次序周游：


5 0 1 2 3 4 5 6 7 8 9


改进后的前序优先次序周游：


5 0 1 2 3 4 5 6 7 8 9


中序优先次序周游：


0 1 2 3 4 5 5 6 7 8 9


后序优先次序周游：


5 4 3 2 1 0 9 8 7 6 5


改进后的后序优先次序周游：


5 4 3 2 1 0 9 8 7 6 5


广度优先优先次序周游：


5 0 6 1 7 2 8 3 9 4 5


4 11
4存在于此二叉树中


11不存在于此二叉树中


所动态申请的内存已被成功释放


Process returned 0 (0x0)   execution time : 9.945 s
Press any key to continue.

#include <cstdio>#include <iostream>#include <string>#include <cmath>#include <algorithm>#include <cstring>#include <map>#include <queue>#include <stack>#define INF 0x3f3f3f3#define ll long longusing namespace std;typedef struct treen * treenode;//定义结构体类型名struct treen{    treenode left;    treenode right;    treenode father;    int data;};treenode head;bool creattree(int firstnum)//创建已申请头指针的二叉树头节点{    if(head == nullptr)    {        treenode tree2 = new treen;//这一行代码也可以表达成：tree * tree2 = new treen        tree2->data = firstnum;        tree2->left = nullptr;        tree2->right = nullptr;        tree2->father = nullptr;        head = tree2;        return true;    }    return false;}bool in_sert(int num)//向已创建的头节点中插入数据元素{    treenode p = head;    if(head == nullptr)    {        treenode tree = new treen;        tree->data = num;        tree->left = nullptr;        tree->right = nullptr;        tree->father = nullptr;        head = tree;        return true;    }    while(1)    {        if(num<=p->data)        {            if(p->left==nullptr)            {                treenode tree= new treen;                tree->data = num;                tree->left = nullptr;                tree->right = nullptr;                tree->father = p;                p->left = tree;                return true;            }            p = p->left;        }        else if(num>p->data)        {            if(p->right==nullptr)            {                treenode tree = new treen;                tree->data = num;                tree->left = nullptr;                tree->right = nullptr;                tree->father = p;                p->right = tree;                return true;            }            p = p->right;        }    }    return false;}bool f_find(int num)//查找变量num代表的数据是否在此二叉树中{    treenode p = head;    if(p == nullptr)    {        return false;    }    else if(p->data == num)        return true;    else    {        while(p != nullptr)        {            if(num<=p->data)            {                p = p->left;                if(p != nullptr && p->data == num)                {                    return true;                }            }            else if(num>p->data)            {                p = p->right;                if(p != nullptr && p->data==num)                {                    return true;                }            }        }        return false;    }}void preorder()//前序优先次序遍历{    treenode p = head;    stack<treenode> sta;    treenode c;    if(p == nullptr) return ;    sta.push(p);    while(!sta.empty())    {        c = sta.top();        sta.pop();        if(c != nullptr)        {            cout<<c->data<<" ";            sta.push(c->right);            sta.push(c->left);        }    }    cout<<endl<<endl;}void preorder1()//改进后的前序优先次序遍历{    treenode p = head;    stack<treenode> sta;    treenode c;    if(p == nullptr) return ;    sta.push(p);    int flag = 1;    while(!sta.empty())    {        c = sta.top();        sta.pop();        if(c->left != nullptr && c->right != nullptr)        {            cout<<c->data<<" ";            sta.push(c->right);            sta.push(c->left);        }        else if(c->left != nullptr && c->right == nullptr)        {            cout<<c->data<<" ";            sta.push(c->left);        }        else if(c->left == nullptr && c->right != nullptr)        {            cout<<c->data<<" ";            sta.push(c->right);        }        else if(c->left == nullptr && c->right == nullptr)        {            cout<<c->data<<" ";        }    }    cout<<endl<<endl;}void inorder()//中序优先次序遍历{    treen t1;    treenode p = head;    stack<treenode> sta;    if(p == nullptr) return ;    do{        while(p != nullptr)        {            sta.push(p);            p = p->left;        }        p = sta.top();        sta.pop();        cout<<p->data<<" ";        p = p->right;    }while(p != nullptr || !sta.empty());    cout<<endl<<endl;}void postorder()//后序优先次序遍历{    struct node    {        int flag;        treenode t;    };    stack<node> sta;    node w;    treenode p = head;    do{        while(p != nullptr)        {            w.t = p;            w.flag = 1;            sta.push(w);            p = p->left;        }        while(!sta.empty())        {            w = sta.top();            sta.pop();            p = w.t;            if(w.flag == 1)            {                w.flag = 2;                sta.push(w);                p = p->right;                break;            }            else cout<<p->data<<" ";        }    }while(!sta.empty());    cout<<endl<<endl;}void postorder1()//改进后的后序优先次序遍历{    stack<treenode> sta;    treenode p = head;    while(p != nullptr || !sta.empty())    {        while(p != nullptr)        {            sta.push(p);            p = p->left ? p->left : p->right;        }        p = sta.top();        sta.pop();        cout<<p->data<<" ";        if(!sta.empty() && sta.top()->left == p)            p = sta.top()->right;        else            p = nullptr;    }    cout<<endl<<endl;}void levelorder()//广度优先次序遍历，也就是宽度优先搜索遍历{    treenode p,pp;    p = head;    queue<treenode> que;    if(p == nullptr) return ;    que.push(p);    while(!que.empty())    {        p = que.front();        que.pop();        cout<<p->data<<" ";        pp = p->left;        if(pp != nullptr) que.push(pp);        pp = p->right;        if(pp != nullptr) que.push(pp);    }    cout<<endl<<endl;}bool de_lete()//释放内存{    treenode p = head;    stack<treenode> sta;    if(p != nullptr)        sta.push(p);    while(!sta.empty())    {        treenode pp = sta.top();        sta.pop();        if(pp->left != nullptr)        {            sta.push(pp->left);        }        if(pp->right != nullptr)        {            sta.push(pp->right);        }        delete pp;    }    if(!sta.empty()) return false;    return true;}int main(){    treenode head = nullptr;    creattree(5);    for(int i = 0; i<10; i++)    {        in_sert(i);    }    cout<<"前序优先次序周游："<<endl<<endl;    preorder();    cout<<"改进后的前序优先次序周游："<<endl<<endl;    preorder1();    cout<<"中序优先次序周游："<<endl<<endl;    inorder();    cout<<"后序优先次序周游："<<endl<<endl;    postorder();    cout<<"改进后的后序优先次序周游："<<endl<<endl;    postorder1();    cout<<"广度优先优先次序周游："<<endl<<endl;    levelorder();    int s,k;    cin>>s>>k;    if(f_find(s))        cout<<s<<"存在于此二叉树中"<<endl<<endl;    else        cout<<s<<"不存在于此二叉树中"<<endl<<endl;    if(f_find(k))        cout<<k<<"存在于此二叉树中"<<endl<<endl;    else        cout<<k<<"不存在于此二叉树中"<<endl<<endl;    if(de_lete())        cout<<"所动态申请的内存已被成功释放"<<endl<<endl;    else cout<<"所动态申请的内存没有成功被释放"<<endl<<endl;    return 0;}