cpp/algorithms/SplayTree.cpp at master · AllAlgorithms/cpp · GitHub

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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;

}

cpp/algorithms/SplayTree.cpp at master · AllAlgorithms/cpp · GitHub

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