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 long
using 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;
}
