add Trie

spec/Trie.spec.mjs

@@ -0,0 +1,36 @@
+
+import {
+  Trie,
+} from '../src/Trie.mjs';
+
+describe('Trie', () => {
+  it('check empty', () => {
+    const trie = Trie();
+    expect(trie.has('')).toBe(false);
+    expect(trie.has('abc')).toBe(false);
+  });
+
+  it('init data', () => {
+    const trie = Trie(['abc', '']);
+    expect(trie.has('')).toBe(true);
+    expect(trie.has('abc')).toBe(true);
+  });
+
+  it('add/readd data', () => {
+    const trie = Trie();
+    expect(trie.has('')).toBe(false);
+    expect(trie.add('')).toBe(true);
+    expect(trie.has('')).toBe(true);
+    expect(trie.add('')).toBe(false);
+  });
+
+  it('list data', () => {
+    const trie = Trie(['abc', '', 'abcdef', 'xyz']);
+    const abc = ['abc', 'abcdef'];
+    expect(trie.get('a')).toEqual(abc);
+    expect(trie.get('ab')).toEqual(abc);
+    expect(trie.get('abc')).toEqual(abc);
+    expect(trie.get('aa')).toEqual([]);
+    expect(trie.get('')).toEqual(['', 'abc', 'abcdef', 'xyz']);
+  });
+});

src/Trie.mjs

@@ -0,0 +1,45 @@
+
+export const Trie = (words = []) => {
+  const HAS = 0;
+  const MAP = 1;
+  const data = [false, new Map()];
+  const add = word => {
+    let node = data;
+    for (let i = 0; i < word.length; ++i) {
+      const char = word[i];
+      if (!node[MAP]) node[MAP] = new Map();
+      const child = node[MAP].get(char) ?? [false];
+      node[MAP].set(char, child);
+      node = child;
+    }
+    if (node[HAS]) return false;
+    node[HAS] = true;
+    return true;
+  };
+  const findNode = word => {
+    let node = data;
+    for (let i = 0; i < word.length; ++i) {
+      const char = word[i];
+      if (!node[MAP]?.has(char)) return [false];
+      node = node[MAP].get(char);
+    }
+    return node;
+  };
+  const has = word => findNode(word)[HAS];
+  const get = begin => {
+    const res = [];
+    const loop = (node, str = '') => {
+      if (!node) return;
+      if (node[HAS]) res.push(begin + str);
+      const map = node[MAP] || new Map();
+      [...map].map(([char, node]) => loop(node, str + char));
+    };
+    loop(findNode(begin));
+    return res;
+  };
+  words.map(word => add(word));
+  return {
+    add, has, get,
+    getData: () => data,
+  };
+};