From JaseWick, source…
Example shows how to search, using Binary Tree, built on 2 pointers linked list
Also a lot of other methods in BST class…
Main and tests
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using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace BinarySearchTreeExample { class Program { static void Main(string[] args) { //Standart_TestClient sc = new Standart_TestClient(); //sc.Execute(); FrequencyCounter_TestClient fct = new FrequencyCounter_TestClient(); fct.Execute(); Console.ReadLine(); } } public class Standart_TestClient { string[] a = { "S", "E", "A", "R", "C", "H", "E", "X", "A", "M", "P", "L", "E" }; public void Execute() { BST<string, int> st = new BST<string, int>(); //Array.Sort(a); // we sort because we use binary search inside //adding for (int i = 0; i < a.Length; i++) { st.put(a[i], i); } if (st.contains("X")) Console.WriteLine("Yes! Contains X"); st.ConsoleDisplay(); st.delete("L"); // Console.WriteLine(); st.ConsoleDisplay(); } } public class FrequencyCounter_TestClient { string[] a = { "S", "E", "A", "R", "C", "H", "E", "X", "A", "M", "P", "L", "E" }; public void Execute() { BST<string, int> st = new BST<string, int>(); //adding for (int i = 0; i < a.Length; i++) { // to Key we write Word, to Value we write Frequency if (!st.contains(a[i])) st.put(a[i], 1); else st.put(a[i], st.get(a[i]) + 1); } st.ConsoleDisplay(); // search max frequent word string maxFrequentWord = " "; st.put(maxFrequentWord, 0); foreach (var val in st) { if ((val != null) && (st.get(val) > st.get(maxFrequentWord))) maxFrequentWord = val; } Console.WriteLine("maxFrequentWord=" + maxFrequentWord + " maxFrequency " + st.get(maxFrequentWord)); st.ConsoleDisplay(); } } } |
Только Get и Put
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class BST<Key, Value> : IEnumerable<Key> where Key : IComparable { private Node root; public class Node { public Key key; public Value val; public Node left,right; // left and right subtrees public int size; // number of nodes in subtree public Node(Key key, Value val, int size) { this.key = key; this.val = val; this.size = size; } } public Value Get(Key key) { return Get(root, key); } private Value Get(Node x, Key key) { if (key == null) throw new ArgumentException("called get() with a null key"); if (x == null) return default(Value); int cmp = key.CompareTo(x.key); if (cmp < 0) return Get(x.left, key); else if (cmp > 0) return Get(x.right, key); else return x.val; } public void Put(Key key, Value val) { root = Put(root, key, val); } public Node Put(Node x,Key key,Value val) { if (x == null) return new Node(key,val,1); int cmp = key.CompareTo(x.key); if (cmp < 0) x.left = Put(x.left, key, val); if (cmp > 0) x.right = Put(x.right, key, val); else x.val = val; x.size = 1 + Size(x.left) + Size(x.right); return x; } // public int Size(Node x) { if (x == null) return 0; else return x.size; } private void TraverseBinaryTreeKey(Node x, ref Queue<Key> q) { if (x != null) { q.Enqueue(x.key); TraverseBinaryTreeKey(x.left, ref q); TraverseBinaryTreeKey(x.right, ref q); } } public IEnumerator<Key> GetEnumerator() { Queue<Key> q = new Queue<Key>(); TraverseBinaryTreeKey(root, ref q); return q.GetEnumerator(); } IEnumerator IEnumerable.GetEnumerator() { return GetEnumerator(); } |
Binary Search tree class…
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using System; using System.Collections.Generic; using System.Diagnostics; using System.Linq; using System.Text; using System.Threading.Tasks; namespace BinarySearchTreeExample { // binary search tree public class BST<Key, Value> : IEnumerable<Key> where Key : IComparable { private Node root; // root of BST private class Node { public Key key; // sorted by key public Value val; // associated data public Node left, right; // left and right subtrees public int size; // number of nodes in subtree public Node(Key key, Value val, int size) { this.key = key; this.val = val; this.size = size; } } /** * Initializes an empty symbol table. */ public BST() { } /** * Returns true if this symbol table is empty. * @return {@code true} if this symbol table is empty; {@code false} otherwise */ public bool isEmpty() { return size() == 0; } /** * Returns the number of key-value pairs in this symbol table. * @return the number of key-value pairs in this symbol table */ public int size() { return size(root); } // return number of key-value pairs in BST rooted at x private int size(Node x) { if (x == null) return 0; else return x.size; } /** * Does this symbol table contain the given key? * * @param key the key * @return {@code true} if this symbol table contains {@code key} and * {@code false} otherwise * @throws IllegalArgumentException if {@code key} is {@code null} */ public bool contains(Key key) { if (key == null) throw new ArgumentException("argument to contains() is null"); return get(key) != null; } /** * Returns the value associated with the given key. * * @param key the key * @return the value associated with the given key if the key is in the symbol table * and {@code null} if the key is not in the symbol table * @throws IllegalArgumentException if {@code key} is {@code null} */ public Value get(Key key) { return get(root, key); } private Value get(Node x, Key key) { if (key == null) throw new ArgumentException("called get() with a null key"); if (x == null) return default(Value); int cmp = key.CompareTo(x.key); if (cmp < 0) return get(x.left, key); else if (cmp > 0) return get(x.right, key); else return x.val; } /** * Inserts the specified key-value pair into the symbol table, overwriting the old * value with the new value if the symbol table already contains the specified key. * Deletes the specified key (and its associated value) from this symbol table * if the specified value is {@code null}. * * @param key the key * @param val the value * @throws IllegalArgumentException if {@code key} is {@code null} */ public void put(Key key, Value val) { if (key == null) throw new ArgumentException("calledput() with a null key"); if (val == null) { delete(key); return; } root = put(root, key, val); Trace.Assert(check()); } private Node put(Node x, Key key, Value val) { if (x == null) return new Node(key, val, 1); int cmp = key.CompareTo(x.key); if (cmp < 0) x.left = put(x.left, key, val); else if (cmp > 0) x.right = put(x.right, key, val); else x.val = val; x.size = 1 + size(x.left) + size(x.right); return x; } /** * Removes the smallest key and associated value from the symbol table. * * @throws NoSuchElementException if the symbol table is empty */ public void deleteMin() { if (isEmpty()) throw new ArgumentException("Symbol table underflow"); root = deleteMin(root); Trace.Assert(check()); } private Node deleteMin(Node x) { if (x.left == null) return x.right; x.left = deleteMin(x.left); x.size = size(x.left) + size(x.right) + 1; return x; } /** * Removes the largest key and associated value from the symbol table. * * @throws NoSuchElementException if the symbol table is empty */ public void deleteMax() { if (isEmpty()) throw new ArgumentException("Symbol table underflow"); root = deleteMax(root); Trace.Assert(check()); } private Node deleteMax(Node x) { if (x.right == null) return x.left; x.right = deleteMax(x.right); x.size = size(x.left) + size(x.right) + 1; return x; } /** * Removes the specified key and its associated value from this symbol table * (if the key is in this symbol table). * * @param key the key * @throws IllegalArgumentException if {@code key} is {@code null} */ public void delete(Key key) { if (key == null) throw new ArgumentException("called delete() with a null key"); root = delete(root, key); Trace.Assert(check()); } private Node delete(Node x, Key key) { if (x == null) return null; int cmp = key.CompareTo(x.key); if (cmp < 0) x.left = delete(x.left, key); else if (cmp > 0) x.right = delete(x.right, key); else { if (x.right == null) return x.left; if (x.left == null) return x.right; Node t = x; x = min(t.right); x.right = deleteMin(t.right); x.left = t.left; } x.size = size(x.left) + size(x.right) + 1; return x; } /** * Returns the smallest key in the symbol table. * * @return the smallest key in the symbol table * @throws NoSuchElementException if the symbol table is empty */ public Key min() { if (isEmpty()) throw new ArgumentException("called min() with empty symbol table"); return min(root).key; } private Node min(Node x) { if (x.left == null) return x; else return min(x.left); } /** * Returns the largest key in the symbol table. * * @return the largest key in the symbol table * @throws NoSuchElementException if the symbol table is empty */ public Key max() { if (isEmpty()) throw new ArgumentException("called max() with empty symbol table"); return max(root).key; } private Node max(Node x) { if (x.right == null) return x; else return max(x.right); } /** * Returns the largest key in the symbol table less than or equal to {@code key}. * * @param key the key * @return the largest key in the symbol table less than or equal to {@code key} * @throws NoSuchElementException if there is no such key * @throws IllegalArgumentException if {@code key} is {@code null} */ public Key floor(Key key) { if (key == null) throw new ArgumentException("argument to floor() is null"); if (isEmpty()) throw new ArgumentException("called floor() with empty symbol table"); Node x = floor(root, key); if (x == null) return default(Key); else return x.key; } private Node floor(Node x, Key key) { if (x == null) return null; int cmp = key.CompareTo(x.key); if (cmp == 0) return x; if (cmp < 0) return floor(x.left, key); Node t = floor(x.right, key); if (t != null) return t; else return x; } /** * Returns the smallest key in the symbol table greater than or equal to {@code key}. * * @param key the key * @return the smallest key in the symbol table greater than or equal to {@code key} * @throws NoSuchElementException if there is no such key * @throws IllegalArgumentException if {@code key} is {@code null} */ public Key ceiling(Key key) { if (key == null) throw new ArgumentException("argument to ceiling() is null"); if (isEmpty()) throw new ArgumentException("called ceiling() with empty symbol table"); Node x = ceiling(root, key); if (x == null) return default(Key); else return x.key; } private Node ceiling(Node x, Key key) { if (x == null) return null; int cmp = key.CompareTo(x.key); if (cmp == 0) return x; if (cmp < 0) { Node t = ceiling(x.left, key); if (t != null) return t; else return x; } return ceiling(x.right, key); } /** * Return the kth smallest key in the symbol table. * * @param k the order statistic * @return the {@code k}th smallest key in the symbol table * @throws IllegalArgumentException unless {@code k} is between 0 and * <em>n</em>–1 */ public Key select(int k) { if (k < 0 || k >= size()) { throw new ArgumentException("called select() with invalid argument: " + k); } Node x = select(root, k); return x.key; } // Return key of rank k. private Node select(Node x, int k) { if (x == null) return null; int t = size(x.left); if (t > k) return select(x.left, k); else if (t < k) return select(x.right, k - t - 1); else return x; } /** * Return the number of keys in the symbol table strictly less than {@code key}. * * @param key the key * @return the number of keys in the symbol table strictly less than {@code key} * @throws IllegalArgumentException if {@code key} is {@code null} */ public int rank(Key key) { if (key == null) throw new ArgumentException("argument to rank() is null"); return rank(key, root); } // Number of keys in the subtree less than key. private int rank(Key key, Node x) { if (x == null) return 0; int cmp = key.CompareTo(x.key); if (cmp < 0) return rank(key, x.left); else if (cmp > 0) return 1 + size(x.left) + rank(key, x.right); else return size(x.left); } //-------- iteraror System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { return GetEnumerator(); } /* public void InOrder_Rec(TNode root) { if (root != null) { InOrder_Rec(root.Left); Console.Write(root.Data +" "); InOrder_Rec(root.Right); } } */ private void TraverseBinaryTreeKey(Node x, ref Queue<Key> q) { if (x != null) { q.Enqueue(x.key); TraverseBinaryTreeKey(x.left,ref q); TraverseBinaryTreeKey(x.right,ref q); } } private void TraverseBinaryTreeValue(Node x, ref Queue<Value> q) { if (x != null) { q.Enqueue(x.val); TraverseBinaryTreeValue(x.left, ref q); TraverseBinaryTreeValue(x.right, ref q); } } public IEnumerator<Key> GetEnumerator() { Queue<Key> q = new Queue<Key>(); TraverseBinaryTreeKey(root, ref q); return q.GetEnumerator(); //foreach (Key key in q) yield return q.Dequeue(key); } public void ConsoleDisplay() { Console.WriteLine(); Console.WriteLine("key" + " " + "val"); Queue<Key> q = new Queue<Key>(); TraverseBinaryTreeKey(root, ref q); Queue<Value> v = new Queue<Value>(); TraverseBinaryTreeValue(root, ref v); Console.WriteLine(); foreach (Key key in q) Console.Write(key + " "); Console.WriteLine(); foreach (Value val in v) Console.Write(val + " "); } /************************************************************************* * Check integrity of BST data structure. ***************************************************************************/ private bool check() { //if (!isBST()) StdOut.println("Not in symmetric order"); if (!isSizeConsistent()) Console.WriteLine("Subtree counts not consistent");// StdOut.println("Subtree counts not consistent"); //if (!isRankConsistent()) StdOut.println("Ranks not consistent"); return isBST() && isSizeConsistent();// && isRankConsistent(); } // does this binary tree satisfy symmetric order? // Note: this test also ensures that data structure is a binary tree since order is strict private bool isBST() { return isBST(root, default(Key), default(Key)); } // is the tree rooted at x a BST with all keys strictly between min and max // (if min or max is null, treat as empty constraint) // Credit: Bob Dondero's elegant solution private bool isBST(Node x, Key min, Key max) { if (x == null) return true; if (min != null && x.key.CompareTo(min) <= 0) return false; if (max != null && x.key.CompareTo(max) >= 0) return false; return isBST(x.left, min, x.key) && isBST(x.right, x.key, max); } // are the size fields correct? private bool isSizeConsistent() { return isSizeConsistent(root); } private bool isSizeConsistent(Node x) { if (x == null) return true; if (x.size != size(x.left) + size(x.right) + 1) return false; return isSizeConsistent(x.left) && isSizeConsistent(x.right); } // check that ranks are consistent /* private bool isRankConsistent() { for (int i = 0; i < size(); i++) if (i != rank(select(i))) return false; for (Key key in keys()) if (key.CompareTo(select(rank(key))) != 0) return false; return true; } */ } } |