add better solution for multi string search question

Author: betomoedano

tries/multi-string-search.js

@@ -0,0 +1,96 @@
+////////////////////////////////////////////
+// MY SOLUTION
+////////////////////////////////////////////
+class PrefixTrie {
+  constructor(string) {
+    this.root = {};
+    this.lastSymbol = "*";
+    this.populateSuffixTrieFrom(string);
+  }
+
+  // Time O(n^2)
+  // Space O(n^2)
+  populateSuffixTrieFrom(string) {
+    for (let i = 0; i < string.length; i++) {
+      this.insertStringFrom(i, string);
+    }
+  }
+
+  insertStringFrom(i, string) {
+    let currentNode = this.root;
+
+    for (let j = i; j < string.length; j++) {
+      const letter = string[j];
+      if (!currentNode.hasOwnProperty(letter)) {
+        currentNode[letter] = {};
+      }
+      currentNode = currentNode[letter];
+    }
+    currentNode[this.lastSymbol] = true;
+  }
+
+  contains(string) {
+    let currentNode = this.root;
+    for (let i = 0; i < string.length; i++) {
+      const letter = string[i];
+      if (!currentNode.hasOwnProperty(letter)) {
+        return false;
+      }
+      currentNode = currentNode[letter];
+    }
+    // return currentNode.hasOwnProperty(this.lastSymbol);
+    return true;
+  }
+}
+// Time O(b^2 + ns)
+// Space O(b^2 + n)
+function multiStringSearch(bigString, smallStrings) {
+  const trie = new PrefixTrie(bigString);
+  return smallStrings.map((string) => trie.contains(string));
+}
+
+////////////////////////////////////////////
+// BETTER SOLUTION
+////////////////////////////////////////////
+class Trie {
+  constructor() {
+    this.root = {};
+    this.endSymbol = "*";
+  }
+
+  insert(string) {
+    let currentNode = this.root;
+
+    for (let i = 0; i < string.length; i++) {
+      const letter = string[i];
+      if (!currentNode.hasOwnProperty(letter)) {
+        currentNode[letter] = {};
+      }
+      currentNode = currentNode[letter];
+    }
+    currentNode[this.endSymbol] = string;
+  }
+}
+// O(ns + bs) time | O(ns) space
+function multiStringSearch(bigString, smallStrings) {
+  const trie = new Trie();
+  for (const string of smallStrings) {
+    trie.insert(string);
+  }
+  const containedStrings = {};
+  for (let i = 0; i < bigString.length; i++) {
+    findSmallStringsIn(bigString, i, trie, containedStrings);
+  }
+  return smallStrings.map((string) => string in containedStrings);
+}
+
+function findSmallStringsIn(string, startIdx, trie, containedStrings) {
+  let currentNode = trie.root;
+  for (let i = startIdx; i < string.length; i++) {
+    const currentChar = string[i];
+    if (!currentNode.hasOwnProperty(currentChar)) break;
+    currentNode = currentNode[currentChar];
+    if (currentNode.hasOwnProperty(trie.endSymbol))
+      containedStrings[currentNode[trie.endSymbol]] = true;
+  }
+}