二进制搜索树是排序的二进制树，其中所有节点将具有以下属性-
节点的右子树的键大于其父节点的键。
节点的左子树的键小于其父节点的键。
所有键值都是不同的。
每个节点不能有两个以上的子节点。
Begin class BST to declare following functions: search() = To search an item in BST. initialize temp = root; while(temp != NULL) Increase depth if(temp→info == data) print data and depth else if(temp→info > data) temp = temp→l; else temp = temp→r; insert() = To insert items in the tree: if tree is empty insert data as root. if tree is not empty if data < root Insert data as left child. else Insert data as right child. del() = To delete an item from tree. casea() = Called from del() if l = r = null. caseb() = Called from del() if l != null, r = null. caseb() = Called from del() if l = null, r != null. casec() = Called from del() if l != null, r != null. inorder() to traverse the node as inorder as: left – root – right. preorder() to traverse the node as preorder as: root – Left – right. postorder() to traverse the node as preorder as: left – right – root End
# include <iostream>
# include <cstdlib>
using namespace std;
struct nod//node declaration
{
int info;
struct nod *l;
struct nod *r;
}*r;
class BST
{
public://functions declaration
void search(nod *, int);
void find(int, nod **, nod **);
void insert(nod *, nod *);
void del(int);
void casea(nod *,nod *);
void caseb(nod *,nod *);
void casec(nod *,nod *);
void preorder(nod *);
void inorder(nod *);
void postorder(nod *);
void show(nod *, int);
BST()
{
r = NULL;
}
};
void BST::find(int i, nod **par, nod **loc)//find the position of the item
{
nod *ptr, *ptrsave;
if (r == NULL)
{
*loc = NULL;
*par = NULL;
return;
}
if (i == r→info)
{
*loc = r;
*par = NULL;
return;
}
if (i < r→info)
ptr = r→l;
else
ptr = r→r;
ptrsave = r;
while (ptr != NULL)
{
if (i == ptr→info)
{
*loc = ptr;
*par = ptrsave;
return;
}
ptrsave = ptr;
if (i < ptr→info)
ptr = ptr→l;
else
ptr = ptr→r;
}
*loc = NULL;
*par = ptrsave;
}
void BST::search(nod *root, int data) //searching
{
int depth = 0;
nod *temp = new nod;
temp = root;
while(temp != NULL)
{
depth++;
if(temp→info == data)
{
cout<<"\nData found at depth: "<<depth<<endl;
return;
}
else if(temp→info > data)
temp = temp→l;
else
temp = temp→r;
}
cout<<"\n Data not found"<<endl;
return;
}
void BST::insert(nod *tree, nod *newnode)
{
if (r == NULL)
{
r = new nod;
r→info = newnode→info;
r→l= NULL;
r→r= NULL;
cout<<"Root Node is Added"<<endl;
return;
}
if (tree→info == newnode→info)
{
cout<<"Element already in the tree"<<endl;
return;
}
if (tree→info > newnode→info)
{
if (tree→l != NULL)
{
insert(tree→l, newnode);
}
else
{
tree→l= newnode;
(tree→l)→l = NULL;
(tree→l)→r= NULL;
cout<<"Node Added To Left"<<endl;
return;
}
}
else
{
if (tree→r != NULL)
{
insert(tree→r, newnode);
}
else
{
tree→r = newnode;
(tree→r)→l= NULL;
(tree→r)→r = NULL;
cout<<"Node Added To Right"<<endl;
return;
}
}
}
void BST::del(int i)
{
nod *par, *loc;
if (r == NULL)
{
cout<<"Tree empty"<<endl;
return;
}
find(i, &par, &loc);
if (loc == NULL)
{
cout<<"Item not present in tree"<<endl;
return;
}
if (loc→l == NULL && loc→r == NULL)
{
casea(par, loc);
cout<<"item deleted"<<endl;
}
if (loc→l!= NULL && loc→r == NULL)
{
caseb(par, loc);
cout<<"item deleted"<<endl;
}
if (loc→l== NULL && loc→r != NULL)
{
caseb(par, loc);
cout<<"item deleted"<<endl;
}
if (loc→l != NULL && loc→r != NULL)
{
casec(par, loc);
cout<<"item deleted"<<endl;
}
free(loc);
}
void BST::casea(nod *par, nod *loc )
{
if (par == NULL)
{
r= NULL;
}
else
{
if (loc == par→l)
par→l = NULL;
else
par→r = NULL;
}
}
void BST::caseb(nod *par, nod *loc)
{
nod *child;
if (loc→l!= NULL)
child = loc→l;
else
child = loc→r;
if (par == NULL)
{
r = child;
}
else
{
if (loc == par→l)
par→l = child;
else
par→r = child;
}
}
void BST::casec(nod *par, nod *loc)
{
nod *ptr, *ptrsave, *suc, *parsuc;
ptrsave = loc;
ptr = loc→r;
while (ptr→l!= NULL)
{
ptrsave = ptr;
ptr = ptr→l;
}
suc = ptr;
parsuc = ptrsave;
if (suc→l == NULL && suc→r == NULL)
casea(parsuc, suc);
else
caseb(parsuc, suc);
if (par == NULL)
{
r = suc;
}
else
{
if (loc == par→l)
par→l = suc;
else
par→r= suc;
}
suc→l = loc→l;
suc→r= loc→r;
}
void BST::preorder(nod *ptr)
{
if (r == NULL)
{
cout<<"Tree is empty"<<endl;
return;
}
if (ptr != NULL)
{
cout<<ptr→info<<" ";
preorder(ptr→l);
preorder(ptr→r);
}
}
void BST::inorder(nod *ptr)//inorder traversal
{
if (r == NULL)
{
cout<<"Tree is empty"<<endl;
return;
}
if (ptr != NULL)
{
inorder(ptr→l);
cout<<ptr→info<<" ";
inorder(ptr→r);
}
}
void BST::postorder(nod *ptr)//postorder traversal
{
if (r == NULL)
{
cout<<"Tree is empty"<<endl;
return;
}
if (ptr != NULL)
{
postorder(ptr→l);
postorder(ptr→r);
cout<<ptr→info<<" ";
}
}
void BST::show(nod *ptr, int level)//print the tree
{
int i;
if (ptr != NULL)
{
show(ptr→r, level+1);
cout<<endl;
if (ptr == r)
cout<<"Root→: ";
else
{
for (i = 0;i < level;i++)
cout<<" ";
}
cout<<ptr→info;
show(ptr→l, level+1);
}
}
int main(){
int c, n,item;
BST bst;
nod *t;
while (1)
{
cout<<"1.Insert Element "<<endl;
cout<<"2.Delete Element "<<endl;
cout<<"3.Search Element"<<endl;
cout<<"4.Inorder Traversal"<<endl;
cout<<"5.Preorder Traversal"<<endl;
cout<<"6.Postorder Traversal"<<endl;
cout<<"7.Display the tree"<<endl;
cout<<"8.Quit"<<endl;
cout<<"Enter your choice : ";
cin>>c;
switch(c)
{
case 1:
t = new nod;
cout<<"Enter the number to be inserted : ";
cin>>t→info;
bst.insert(r, t);
break;
case 2:
if (r == NULL)
{
cout<<"Tree is empty, nothing to delete"<<endl;
continue;
}
cout<<"Enter the number to be deleted : ";
cin>>n;
bst.del(n);
break;
case 3:
cout<<"Search:"<<endl;
cin>>item;
bst.search(r,item);
break;
case 4:
cout<<"BST的有序遍历："<<endl;
bst.inorder(r);
cout<<endl;
break;
case 5:
cout<<"BST的预遍历："<<endl;
bst.preorder(r);
cout<<endl;
break;
case 6:
cout<<"BST的事后遍历："<<endl;
bst.postorder(r);
cout<<endl;
break;
case 7:
cout<<"显示BST："<<endl;
bst.show(r,1);
cout<<endl;
break;
case 8:
exit(1);
default:
cout<<"Wrong choice"<<endl;
}
}
}输出结果
1.Insert Element 2.Delete Element 3.Search Element 4.Inorder Traversal 5.Preorder Traversal 6.Postorder Traversal 7.Display the tree 8.Quit Enter your choice : 1 Enter the number to be inserted : 6 Root Node is Added 1.Insert Element 2.Delete Element 3.Search Element 4.Inorder Traversal 5.Preorder Traversal 6.Postorder Traversal 7.Display the tree 8.Quit Enter your choice : 1 Enter the number to be inserted : 7 Node Added To Right 1.Insert Element 2.Delete Element 3.Search Element 4.Inorder Traversal 5.Preorder Traversal 6.Postorder Traversal 7.Display the tree 8.Quit Enter your choice : 1 Enter the number to be inserted : 5 Node Added To Left 1.Insert Element 2.Delete Element 3.Search Element 4.Inorder Traversal 5.Preorder Traversal 6.Postorder Traversal 7.Display the tree 8.Quit Enter your choice : 1 Enter the number to be inserted : 4 Node Added To Left 1.Insert Element 2.Delete Element 3.Search Element 4.Inorder Traversal 5.Preorder Traversal 6.Postorder Traversal 7.Display the tree 8.Quit Enter your choice : 3 Search: 7 Data found at depth: 2 1.Insert Element 2.Delete Element 3.Search Element 4.Inorder Traversal 5.Preorder Traversal 6.Postorder Traversal 7.Display the tree 8.Quit Enter your choice : 3 Search: 1 Data not found 1.Insert Element 2.Delete Element 3.Search Element 4.Inorder Traversal 5.Preorder Traversal 6.Postorder Traversal 7.Display the tree 8.Quit Enter your choice : 4 BST的有序遍历： 4 5 6 7 1.Insert Element 2.Delete Element 3.Search Element 4.Inorder Traversal 5.Preorder Traversal 6.Postorder Traversal 7.Display the tree 8.Quit Enter your choice : 5 BST的预遍历： 6 5 4 7 1.Insert Element 2.Delete Element 3.Search Element 4.Inorder Traversal 5.Preorder Traversal 6.Postorder Traversal 7.Display the tree 8.Quit Enter your choice : 6 BST的事后遍历： 4 5 7 6 1.Insert Element 2.Delete Element 3.Search Element 4.Inorder Traversal 5.Preorder Traversal 6.Postorder Traversal 7.Display the tree 8.Quit Enter your choice : 7 显示BST： 7 Root→: 6 5 4 1.Insert Element 2.Delete Element 3.Search Element 4.Inorder Traversal 5.Preorder Traversal 6.Postorder Traversal 7.Display the tree 8.Quit Enter your choice : 2 Enter the number to be deleted : 1 Item not present in tree 1.Insert Element 2.Delete Element 3.Search Element 4.Inorder Traversal 5.Preorder Traversal 6.Postorder Traversal 7.Display the tree 8.Quit Enter your choice : 5 BST的预遍历： 6 5 4 7 1.Insert Element 2.Delete Element 3.Search Element 4.Inorder Traversal 5.Preorder Traversal 6.Postorder Traversal 7.Display the tree 8.Quit Enter your choice : 2 Enter the number to be deleted : 5 item deleted 1.Insert Element 2.Delete Element 3.Search Element 4.Inorder Traversal 5.Preorder Traversal 6.Postorder Traversal 7.Display the tree 8.Quit Enter your choice : 7 显示BST： 7 Root→: 6 4 1.Insert Element 2.Delete Element 3.Search Element 4.Inorder Traversal 5.Preorder Traversal 6.Postorder Traversal 7.Display the tree 8.Quit Enter your choice : 8