Feat: 211. Design Add and Search Words Data Structure

Author: HC-kang

design-add-and-search-words-data-structure/HC-kang.ts

@@ -0,0 +1,102 @@
+/**
+ * https://leetcode.com/problems/design-add-and-search-words-data-structure
+ */
+// Using Trie
+class WordDictionary {
+  constructor(private root: Record<string, any> = {}) {}
+
+  /**
+   * T.C. O(L) L: length of a word
+   * S.C. O(L)
+   */
+  addWord(word: string): void {
+    let node = this.root;
+    for (const char of word) {
+      if (!node[char]) {
+        node[char] = {};
+      }
+      node = node[char];
+    }
+    node['isEnd'] = true;
+  }
+
+  /**
+   * T.C. O(N) - there are only 2 dots in the word(26 * 26 * N)
+   * S.C. O(N * L) N: number of words, L: length of a word
+   */
+  search(word: string): boolean {
+    return this.dfs(word, this.root);
+  }
+
+  private dfs(word: string, node: Record<string, any>): boolean {
+    for (let i = 0; i < word.length; i++) {
+      if (word[i] === '.') {
+        for (const key in node) {
+          if (this.dfs(word.slice(i + 1), node[key])) {
+            return true;
+          }
+        }
+        return false;
+      }
+      if (!node[word[i]]) {
+        return false;
+      }
+      node = node[word[i]];
+    }
+    return !!node['isEnd'];
+  }
+}
+
+// Using Array and Set
+class WordDictionary {
+  constructor(
+    private words: Set<string>[] = Array.from({ length: 25 }, () => new Set())
+  ) {}
+
+  /**
+   * T.C. O(1)
+   * S.C. O(N * L)
+   */
+  addWord(word: string): void {
+    this.words[word.length - 1].add(word);
+  }
+
+  /**
+   * T.C. O(N * L) N: number of words, L: length of a word
+   * S.C. O(1)
+   */
+  search(word: string): boolean {
+    const hasDot = word.indexOf('.') !== -1;
+    const set = this.words[word.length - 1];
+
+    if (!hasDot) {
+      return set.has(word);
+    }
+
+    for (const w of set) {
+      let i = 0;
+      while (i < word.length) {
+        if (word[i] == '.') {
+          i++;
+          continue;
+        }
+        if (word[i] !== w[i]) {
+          break;
+        }
+        i++;
+      }
+
+      if (i === word.length) {
+        return true;
+      }
+    }
+    return false;
+  }
+}
+
+/**
+ * Your WordDictionary object will be instantiated and called as such:
+ * var obj = new WordDictionary()
+ * obj.addWord(word)
+ * var param_2 = obj.search(word)
+ */