implement-trie-prefix-tree solutions

Author: Blossssom

implement-trie-prefix-tree/Blossssom.ts

@@ -0,0 +1,99 @@
+// 단순 구현 시 효율이 낮게 나옴
+// class Trie {
+//   private word: Set<string>;
+//   constructor() {
+//     this.word = new Set();
+//   }
+
+//   insert(word: string): void {
+//     this.word.add(word);
+//   }
+
+//   search(word: string): boolean {
+//     return this.word.has(word);
+//   }
+
+//   startsWith(prefix: string): boolean {
+//     for (const str of this.word) {
+//       if (prefix.length > str.length) {
+//         continue;
+//       }
+//       let check = true;
+//       for (let i = 0; i < prefix.length; i++) {
+//         if (str[i] !== prefix[i]) {
+//           check = false;
+//           break;
+//         }
+//       }
+//       if (check) {
+//         return true;
+//       }
+//     }
+//     return false;
+//   }
+// }
+
+// 노드 구조를 개선
+class TrieNode {
+  children: { [key: string]: TrieNode };
+  isEndOfWord: boolean;
+  constructor() {
+    this.children = {};
+    this.isEndOfWord = false;
+  }
+}
+
+class Trie {
+  private root: TrieNode;
+  constructor() {
+    this.root = new TrieNode();
+  }
+
+  insert(word: string): void {
+    // 글자 하나씩 TrieNode 타입으로 저장
+    let currentNode = this.root;
+    for (const char of word) {
+      if (!currentNode.children[char]) {
+        currentNode.children[char] = new TrieNode();
+      }
+
+      currentNode = currentNode.children[char];
+    }
+    currentNode.isEndOfWord = true;
+    console.log(this.root);
+  }
+
+  // 각 글자를 TrieNode에서 서칭하며 판단
+  search(word: string): boolean {
+    let currentNode = this.root;
+    for (const char of word) {
+      if (!currentNode.children[char]) {
+        return false;
+      }
+      currentNode = currentNode.children[char];
+    }
+    return currentNode.isEndOfWord;
+  }
+
+  // 동일 로직이지만 prefix 만큼만 존재하면 true
+  startsWith(prefix: string): boolean {
+    let currentNode = this.root;
+    for (const char of prefix) {
+      if (!currentNode.children[char]) {
+        return false;
+      }
+      currentNode = currentNode.children[char];
+    }
+    return true;
+  }
+}
+
+const trie = new Trie();
+trie.insert("apple");
+trie.search("apple"); // true
+trie.search("app"); // false
+trie.startsWith("app"); // true
+trie.insert("app");
+trie.search("app"); // true
+
+