Implement Trie (Prefix Tree)

Author: casentino

implement-trie-prefix-tree/casentino.ts

@@ -0,0 +1,55 @@
+type ChildTrie = {
+  value?: string;
+  isEnd?: boolean;
+  childrens: ChildrenMap;
+};
+type ChildrenMap = {
+  [key: string]: ChildTrie;
+};
+
+class Trie {
+  childrens: ChildrenMap = {};
+  constructor() {}
+
+  insert(word: string): void {
+    if (word.length === 0) {
+      return;
+    }
+    let current: ChildTrie = {
+      childrens: this.childrens,
+    };
+    for (let i = 0; i < word.length; i++) {
+      if (current.childrens[word[i]] === undefined) {
+        current.childrens[word[i]] = { value: word[i], isEnd: false, childrens: {} };
+      }
+
+      current = current.childrens[word[i]];
+    }
+    current.isEnd = true;
+  }
+
+  search(word: string): boolean {
+    let current: ChildTrie = {
+      childrens: this.childrens,
+    };
+    for (let i = 0; i < word.length; i++) {
+      if (current.childrens[word[i]] === undefined) {
+        return false;
+      }
+
+      current = current.childrens[word[i]];
+    }
+    return current.isEnd ?? false;
+  }
+
+  startsWith(prefix: string): boolean {
+    let current = this.childrens;
+    for (let i = 0; i < prefix.length; i++) {
+      if (current[prefix[i]] === undefined) {
+        return false;
+      }
+      current = current[prefix[i]].childrens;
+    }
+    return true;
+  }
+}