trie class + dfs O(n) O(n)

Author: lukeist

leetcode-1268-searchSuggestionsSystem-2.js

@@ -0,0 +1,93 @@
+/**
+ * @param {string[]} products
+ * @param {string} searchWord
+ * @return {string[][]}
+ */
+
+// p: arr, str
+// r: arr
+
+//                                      m
+//                                      |
+//                                      o
+//                              /       /        \
+//                              b      n         u
+//                              |      / \         |
+//                               i     e  i          s
+//
+// create a class TrieNode
+class TrieNode {
+  constructor() {
+    this.isWord = false;
+    this.children = new Array(26).fill(null);
+  }
+}
+//             a b c d e f g h i j k l m n o p
+// children = [x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x]
+// create a class Trie
+class Trie {
+  constructor() {
+    this.root = new TrieNode();
+    this.alphabet = "abcdefghijklmnopqrstuvwxyz";
+  }
+
+  // insert words from arr to class Trie
+  insert(word) {
+    let c = this.root;
+    let a = this.alphabet;
+    for (let w of word) {
+      let i = a.indexOf(w);
+      !c.children[i] && (c.children[i] = new TrieNode());
+      c = c.children[i];
+    }
+    c.isWord = true;
+  }
+
+  // add words to result array following each prefix
+  getWordsStartWith(prefix) {
+    let c = this.root;
+    let a = this.alphabet;
+    const result = [];
+    for (let p of prefix) {
+      let i = a.indexOf(p);
+      if (!c.children[i]) return result;
+      c = c.children[i];
+    }
+
+    this.dfsGetWords(prefix, c, result);
+    return result;
+  }
+
+  // dfs to get words following prefixes
+  dfsGetWords(prefix, c, result) {
+    if (result.length === 3) return;
+    c.isWord && result.push(prefix);
+    let a = this.alphabet;
+    for (let i = 0; i < a.length; i++) {
+      c.children[i] && this.dfsGetWords(prefix + a[i], c.children[i], result);
+    }
+  }
+}
+
+var suggestedProducts = function (products, searchWord) {
+  // create new Trie
+  const trie = new Trie();
+  // insert words
+  for (let p of products) {
+    trie.insert(p);
+  }
+  const result = [];
+  let prefix = "";
+  // add words to result array
+  for (let w of searchWord) {
+    prefix += w;
+    result.push(trie.getWordsStartWith(prefix));
+  }
+
+  // return result array
+  return prefix;
+};
+
+const products = ["mobile", "mouse", "moneypot", "monitor", "mousepad"];
+const searchWord = "mouse";
+console.log(suggestedProducts(products, searchWord));