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Unformatted text preview: Binary search tree From Wikipedia, the free encyclopedia In computer science, a binary search tree ( BST ) is a binary tree data structure which has the following properties: ¡ each node (item in the tree) has a value; ¡ a total order (linear order) is defined on these values; ¡ the left subtree of a node contains only values less than the node's value; ¡ the right subtree of a node contains only values greater than or equal to the node's value. The major advantage of binary search trees over other data structures is that the related sorting algorithms and search algorithms such as in-order traversal can be very efficient. Binary search trees can choose to allow or disallow duplicate values, depending on the implementation. Binary search trees are a fundamental data structure used to construct more abstract data structures such as sets, multisets, and associative arrays. Operations Operations on a binary tree require comparisons between nodes. These comparisons are made with calls to a comparator, which is a subroutine that computes the total order (linear order) on any two values. This comparator can be explicitly or implicitly defined, depending on the language in which the BST is implemented. Searching Searching a binary tree for a specific value can be a recursive or iterative process. This explanation covers a recursive method. We begin by examining the root node. If the tree is null, the value we are searching for does not exist in the tree. Otherwise, if the value equals the root, the search is successful. If the value is less than the root, search the left subtree. Similarly, if it is greater than the root, search the right subtree. This process is repeated until the value is found or the indicated subtree is null. If the searched value is not found before a null subtree is reached, then the item must not be present in the tree. Here is the search algorithm in the Python programming language: A binary search tree of size 9 and depth 3, with root 8 and leaves 1, 4, 7 and 13 Contents ¡ 1 Operations ¡ 1.1 Searching ¡ 1.2 Insertion ¡ 1.3 Deletion ¡ 1.4 Traversal ¡ 1.5 Sort ¡ 1.6 Example for a Binary Search Tree in Python: ¡ 2 Types of binary search trees ¡ 2.1 Performance comparisons ¡ 2.2 Optimal binary search trees ¡ 3 See also ¡ 4 References ¡ 5 Further reading ¡ 6 External links Wikipedia is sustained by people like you. Please donate today. This operation requires O(log n ) time in the average case, but needs O( n ) time in the worst-case, when the unbalanced tree resembles a linked list (degenerate tree). Insertion Insertion begins as a search would begin; if the root is not equal to the value, we search the left or right subtrees as before....
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This note was uploaded on 04/20/2010 for the course CS CS206 taught by Professor Lee during the Fall '09 term at 카이스트, 한국과학기술원.
- Fall '09
- Binary Search