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SplayTree.cpp
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249 lines (237 loc) · 6.86 KB
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#include <iostream>
#include <cstdio>
#include <cstdlib>
using namespace std;
struct splay
{
int key;
splay* lchild;
splay* rchild;
};
class SplayTree
{
public:
SplayTree()
{
}
// RR(Y rotates to the right)
splay* RR_Rotate(splay* k2)
{
splay* k1 = k2->lchild;
k2->lchild = k1->rchild;
k1->rchild = k2;
return k1;
}
// LL(Y rotates to the left)
splay* LL_Rotate(splay* k2)
{
splay* k1 = k2->rchild;
k2->rchild = k1->lchild;
k1->lchild = k2;
return k1;
}
// An implementation of top-down splay tree
splay* Splay(int key, splay* root)
{
if (!root)
return NULL;
splay header;
/* header.rchild points to L tree;
header.lchild points to R Tree */
header.lchild = header.rchild = NULL;
splay* LeftTreeMax = &header;
splay* RightTreeMin = &header;
while (1)
{
if (key < root->key)
{
if (!root->lchild)
break;
if (key < root->lchild->key)
{
root = RR_Rotate(root);
// only zig-zig mode need to rotate once,
if (!root->lchild)
break;
}
/* Link to R Tree */
RightTreeMin->lchild = root;
RightTreeMin = RightTreeMin->lchild;
root = root->lchild;
RightTreeMin->lchild = NULL;
}
else if (key > root->key)
{
if (!root->rchild)
break;
if (key > root->rchild->key)
{
root = LL_Rotate(root);
// only zag-zag mode need to rotate once,
if (!root->rchild)
break;
}
/* Link to L Tree */
LeftTreeMax->rchild = root;
LeftTreeMax = LeftTreeMax->rchild;
root = root->rchild;
LeftTreeMax->rchild = NULL;
}
else
break;
}
/* assemble L Tree, Middle Tree and R tree */
LeftTreeMax->rchild = root->lchild;
RightTreeMin->lchild = root->rchild;
root->lchild = header.rchild;
root->rchild = header.lchild;
return root;
}
splay* New_Node(int key)
{
splay* p_node = new splay;
if (!p_node)
{
fprintf(stderr, "Out of memory!\n");
exit(1);
}
p_node->key = key;
p_node->lchild = p_node->rchild = NULL;
return p_node;
}
splay* Insert(int key, splay* root)
{
static splay* p_node = NULL;
if (!p_node)
p_node = New_Node(key);
else
p_node->key = key;
if (!root)
{
root = p_node;
p_node = NULL;
return root;
}
root = Splay(key, root);
/* This is BST that, all keys <= root->key is in root->lchild, all keys >
root->key is in root->rchild. */
if (key < root->key)
{
p_node->lchild = root->lchild;
p_node->rchild = root;
root->lchild = NULL;
root = p_node;
}
else if (key > root->key)
{
p_node->rchild = root->rchild;
p_node->lchild = root;
root->rchild = NULL;
root = p_node;
}
else
return root;
p_node = NULL;
return root;
}
splay* Delete(int key, splay* root)
{
splay* temp;
if (!root)
return NULL;
root = Splay(key, root);
if (key != root->key)
return root;
else
{
if (!root->lchild)
{
temp = root;
root = root->rchild;
}
else
{
temp = root;
/*Note: Since key == root->key,
so after Splay(key, root->lchild),
the tree we get will have no right child tree.*/
root = Splay(key, root->lchild);
root->rchild = temp->rchild;
}
free(temp);
return root;
}
}
splay* Search(int key, splay* root)
{
return Splay(key, root);
}
void InOrder(splay* root)
{
if (root)
{
InOrder(root->lchild);
cout<< "key: " <<root->key;
if(root->lchild)
cout<< " | left child: "<< root->lchild->key;
if(root->rchild)
cout << " | right child: " << root->rchild->key;
cout<< "\n";
InOrder(root->rchild);
}
}
};
int main()
{
SplayTree st;
int vector[10] = {9,8,7,6,5,4,3,2,1,0};
splay *root;
root = NULL;
const int length = 10;
int i;
for(i = 0; i < length; i++)
root = st.Insert(vector[i], root);
cout<<"\nInOrder: \n";
st.InOrder(root);
int input, choice;
while(1)
{
cout<<"\nSplay Tree Operations\n";
cout<<"1. Insert "<<endl;
cout<<"2. Delete"<<endl;
cout<<"3. Search"<<endl;
cout<<"4. Exit"<<endl;
cout<<"Enter your choice: ";
cin>>choice;
switch(choice)
{
case 1:
cout<<"Enter value to be inserted: ";
cin>>input;
root = st.Insert(input, root);
cout<<"\nAfter Insert: "<<input<<endl;
st.InOrder(root);
break;
case 2:
cout<<"Enter value to be deleted: ";
cin>>input;
root = st.Delete(input, root);
cout<<"\nAfter Delete: "<<input<<endl;
st.InOrder(root);
break;
case 3:
cout<<"Enter value to be searched: ";
cin>>input;
root = st.Search(input, root);
cout<<"\nAfter Search "<<input<<endl;
st.InOrder(root);
break;
case 4:
exit(1);
default:
cout<<"\nInvalid type! \n";
}
}
cout<<"\n";
return 0;
}