116 lines
2.7 KiB
C++
116 lines
2.7 KiB
C++
/* B-Tree
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* Author: Caleb Baker
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* Date: 10/8/17
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* Summary: A B-Tree data structure.
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* Most standard operations run in O(lg(n)) time.
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* Uses O(n) memory.
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* Where n is the number of items in the tree.
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*/
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#pragma once
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#include <utility>
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// #define NULL 0
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#define SEARCH_KEY_NOT_FOUND 's'
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#define REMOVE_KEY_NOT_FOUND 'r'
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// struct for representing nodes of a b tree
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template <typename T>
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struct BNode {
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BNode<T> **child; // Array of pointers to children.
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T *key; // Array of keys.
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unsigned size; // Number of keys.
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bool leaf; // Whether the node is a leaf.
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};
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typedef char BTREE_EXCEPTION;
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// class for representing b trees.
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template <typename T>
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class BTree {
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public:
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// Constructor
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// First parameter is the minimum degree of the tree.
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// Second parameter is the tree's key-comparison function.
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// Third parameter is a function that prints keys.
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// Constant time.
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BTree(unsigned, bool (*)(T, T), void (*)(T) = NULL);
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// Destructor.
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// Linear time.
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~BTree<T>();
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// Inserts a key into the tree.
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// Logorithmic time.
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void insert(T);
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// Removes a key from the tree.
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// Throws a BTREE_EXCEPTION if no item was found to remove.
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// Logorithmic time.
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T remove(T);
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// Function to find a key in the tree.
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// returnValue.first is the node the item is in.
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// returnValue.second is the correct index in that node's key array
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// Logorithmic time.
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std::pair<BNode<T>*, unsigned> search(T);
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// Uses search but just returns the key rather than the whole node.
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// Useful when T is a key value pair and lessThan only looks at the key.
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// Throws a BTREE_EXCEPTION if no item matching the parameter is found
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// Logorithmic time.
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T searchKey(T);
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// Prints the tree.
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// Linear time
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void print();
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private:
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// Used for initializing nodes.
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void initializeNode(BNode<T>*);
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// Recursive function called by destructor.
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void freeNode(BNode<T>*);
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// Finds the index of a key in a node.
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unsigned findIndex(BNode<T>*, T);
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// Inserts a key into a node.
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unsigned nodeInsert(BNode<T>*, T);
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// Deletes the key at a given index from a node.
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T nodeDelete(BNode<T>*, unsigned);
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// Function for splitting nodes that are too full.
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void splitChild(BNode<T>*, int);
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// Merges two children of a node at a given index into one child.
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char mergeChildren(BNode<T>*, unsigned);
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// Makes sure the child of a node at a specified index has >= minDegree items.
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char fixChildSize(BNode<T>*, unsigned);
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// Recursively prints a subtree.
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void printNode(BNode<T>*, unsigned);
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// Root node.
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BNode<T> *root;
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// Comparison function used for managing element placement.
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bool (*lessThan)(T, T);
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// Function used to print items in the tree.
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void (*printKey)(T);
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// Minimum degree of the tree.
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unsigned minDegree;
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};
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#include "bTree.cpp" |