Add Trie

data_structures/Trie/Trie.swift

@@ -0,0 +1,196 @@
+//
+//  Trie.swift
+//  
+//
+//  Created by Moon Jongseek on 11/27/24.
+//
+
+import Foundation
+
+/// Trie(Prefix Tree)
+///
+/// A Trie/Prefix Tree is a kind of search tree used
+/// to provide quick lookup of words/patterns in a set of words.
+final class Trie {
+
+    /// The child node dictionary
+    ///
+    /// Key is `String` type, and value is `Trie` type
+    private var child: [String: Trie] = [:]
+
+    /// A Boolean value indicating whether this node is leaf node.
+    ///
+    /// A Leaf node means that the child is empty.
+    /// This property is `false` when the object is initialized.
+    private var isLeaf: Bool = false
+
+    public init() {
+
+    }
+
+    /// Inserts an word into the trie.
+    ///
+    /// The following example shows how to insert an word:
+    ///
+    ///     let trie = Trie()
+    ///     trie.insert(word: "Trie")
+    ///
+    /// - Parameters:
+    ///   - word: A string data to insert into trie.
+    public func insert(word: String) {
+        var node = self
+        for s in word {
+            let key = "\(s)"
+            node.child[key] = (node.child[key] ?? Trie())
+            node = node.child[key]!
+        }
+        node.isLeaf = true
+    }
+
+    /// Inserts the multiple words into the trie
+    /// by using `insert(word: String)`.
+    ///
+    /// The following example shows how to insert multiple words:
+    ///
+    ///     let trie = Trie()
+    ///     trie.insert(words: ["Trie", "Tree", "Swift"])
+    ///
+    /// - Parameters:
+    ///   - words: An array containing string data to insert into trie.
+    public func insert(words: [String]) {
+        for word in words {
+            self.insert(word: word)
+        }
+    }
+
+    /// Deletes the word from the trie.
+    ///
+    /// The following example shows how to delete an word:
+    ///
+    ///     let trie = Trie()
+    ///     trie.insert(words: ["Trie", "Tree", "Swift"])
+    ///     print(trie.delete(word: "Trie"))
+    ///     // Prints "true"
+    ///     print(trie.delete(word: "Three"))
+    ///     // Prints "false"
+    ///     print(getAllWords())
+    ///     // Prints "["Tree", "Swift"]"
+    ///
+    /// - Parameters:
+    ///   - word: A string data to delete from trie.
+    ///
+    /// - Returns: A boolean indicating whether the deletion was successful.
+    public func delete(word: String) -> Bool {
+        var root = self
+        var keys = Array(word).map(String.init)
+        func _delete(_ node: Trie, _ depth: Int) -> Bool {
+            if depth == word.count {
+                guard node.isLeaf else {
+                    return false
+                }
+                node.isLeaf = false
+                return true
+            }
+            guard let c = node.child[keys[depth]] else {
+                return false
+            }
+            let isDeleteChildNode = _delete(c, depth + 1)
+
+            if isDeleteChildNode {
+                if c.child.isEmpty && !c.isLeaf {
+                    node.child[keys[depth]] = nil
+                }
+            }
+            return isDeleteChildNode
+        }
+        return _delete(root, 0)
+    }
+
+    /// Delete the multiple words from the trie
+    /// by using `delete(word: String)`.
+    ///
+    /// The following example shows how to delete multiple words:
+    ///
+    ///     let trie = Trie()
+    ///     trie.insert(words: ["Trie", "Tree", "Swift"])
+    ///     print(trie.delete(words: ["Trie", "Three"]))
+    ///     // Prints "["Trie": true, "Three": false]"
+    ///     print(getAllWords())
+    ///     // Prints "["Tree", "Swift"]"
+    ///
+    /// - Parameters:
+    ///   - words: An array containing string data to delete from trie.
+    ///
+    /// - Returns: A dictionary where the keys are strings representing each data item, and the values are booleans indicating whether the deletion was successful.
+    public func delete(words: [String]) -> [String: Bool] {
+        var result: [String: Bool] = [:]
+        for word in words {
+            result[word] = self.delete(word: word)
+        }
+        return result
+    }
+
+    /// Returns a Boolean value indicating whether the trie contains the
+    /// given string data.
+    ///
+    /// This example checks to see whether a word is in the trie.
+    ///
+    ///     let trie = Trie()
+    ///     trie.insert(words: ["Trie", "Tree", "Swift"])
+    ///     print(trie.contains(word: "Trie"))
+    ///     // Prints "true"
+    ///     print(trie.contains(word: "Three"))
+    ///     // Prints "false"
+    ///
+    /// - Parameters:
+    ///   - words: The `String` element to find in the trie.
+    ///
+    /// - Returns: `true` if the trie contains a `String` element that satisfies
+    ///   `word`; otherwise, `false`.
+    public func contains(word: String) -> Bool {
+        var node = self
+        for s in word {
+            guard let c = node.child["\(s)"] else {
+                return false
+            }
+            node = c
+        }
+        return node.isLeaf
+    }
+
+    /// A array contained string value inserted in trie.
+    ///
+    /// The results are not affected by the order of insertion.
+    /// The following example shows how to get all of string in trie:
+    ///
+    ///     let trie = Trie()
+    ///     trie.insert(words: ["Trie", "Tree", "Swift"])
+    ///     print(trie.getAllWords())
+    ///     // Prints "["Trie", "Tree", "Swift"]"
+    ///
+    /// - Returns: An array of the string in trie.
+    public func getAllWords() -> [String] {
+        var node = self
+        var result: [String] = []
+        for c in node.child {
+            if c.value.isLeaf {
+                result += ["\(c.key)"]
+            }
+            result += c.value.getAllWords().map { "\(c.key)\($0)" }
+        }
+        return result
+    }
+}
+
+
+let trie = Trie()
+trie.insert(words: ["Swift", "Apple", "iPhone", "iPad", "iMac", "AppleWatch"])
+print(trie.getAllWords())
+
+print(trie.contains(word: "Apple"))
+print(trie.delete(words: ["Apple", "iP"]))
+print(trie.contains(word: "Apple"))
+print(trie.getAllWords())
+
+print(trie.contains(word: "AppleWatch"))
+print(trie.contains(word: "iP"))