add: 230317

cpp/2303/230317.cpp

@@ -0,0 +1,69 @@
+#include <string>
+#include <iostream>
+
+/**
+ * 208. Implement Trie (Prefix Tree)
+ *
+ * A trie (pronounced as "try") or prefix tree is a tree data structure used to efficiently store and retrieve keys in a dataset of strings. There are various applications of this data structure, such as autocomplete and spellchecker.
+ *
+ * Implement the Trie class:
+ *
+ * Trie() Initializes the trie object.
+ * void insert(String word) Inserts the string word into the trie.
+ * boolean search(String word) Returns true if the string word is in the trie (i.e., was inserted before), and false otherwise.
+ * boolean startsWith(String prefix) Returns true if there is a previously inserted string word that has the prefix prefix, and false otherwise.
+ */
+
+struct TrieNode {
+	TrieNode* p[26] = {};
+	bool terminate = false;
+};
+
+class Trie {
+private:
+	TrieNode r;
+
+public:
+	Trie() = default;
+
+	void insert(const std::string& word) {
+		TrieNode* ptr = &this->r;
+		for (char i : word) {
+			if (!ptr->p[i - 'a'])
+				ptr->p[i - 'a'] = new TrieNode;
+			ptr = ptr->p[i - 'a'];
+		}
+		ptr->terminate = true;
+	}
+
+	bool search(const std::string& word) const {
+		const TrieNode* ptr = &this->r;
+		for (char i : word) {
+			if (!ptr->p[i - 'a'])
+				return false;
+			ptr = ptr->p[i - 'a'];
+		}
+		return ptr && ptr->terminate;
+	}
+
+	bool startsWith(const std::string& prefix) const {
+		const TrieNode* ptr = &this->r;
+		for (char i : prefix) {
+			if (!ptr->p[i - 'a'])
+				return false;
+			ptr = ptr->p[i - 'a'];
+		}
+		return ptr;
+	}
+};
+
+int main() {
+	Trie trie;
+	trie.insert("apple");
+	std::cout << trie.search("apple");   // return True
+	std::cout << trie.search("app");     // return False
+	std::cout << trie.startsWith("app"); // return True
+	trie.insert("app");
+	std::cout << trie.search("app");     // return True
+	return 0;
+}

cpp/2303/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2303)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2303 230317-CN.cpp)
+ADD_EXECUTABLE(2303 230317.cpp)