Find the Length of the Longest Common Prefix

export function longestCommonPrefix(arr1: number[], arr2: number[]): number {
  const prefixes = new Set<number>();
  for (const num of arr1) {
    for (const prefix of getPrefix(num)) {
      prefixes.add(prefix);
    }
  }
 
  let answer = 0;
  for (const num of arr2) {
    for (const prefix of getPrefix(num)) {
      if (prefixes.has(prefix)) {
        answer = Math.max(answer, Math.floor(Math.log10(prefix)) + 1);
      }
    }
  }
  return answer;
}
 
function* getPrefix(num: number) {
  let curr = num;
  while (0 < curr) {
    yield curr;
    curr = Math.floor(curr / 10);
  }
}

export function longestCommonPrefix(arr1: number[], arr2: number[]): number {
  const trie = new Trie(arr1);
  return arr2.reduce((prev, num) => Math.max(prev, trie.findLongestPrefix(num)), 0);
}
 
class TrieNode {
  children: Array<TrieNode | null>;
 
  constructor() {
    this.children = new Array(10).fill(null);
  }
}
 
class Trie {
  private readonly root: TrieNode;
 
  constructor(arr: number[]) {
    this.root = new TrieNode();
    arr.forEach((num) => this.insert(num));
  }
 
  insert(num: number): void {
    let node = this.root;
    for (const digit of String(num)) {
      const i = parseInt(digit);
      const childNode = node.children[i];
      if (childNode !== null) {
        node = childNode;
      } else {
        const newNode = new TrieNode();
        node.children[i] = newNode;
        node = newNode;
      }
    }
  }
 
  findLongestPrefix(num: number): number {
    let node = this.root;
    let maxLength = 0;
    for (const digit of String(num)) {
      const i = parseInt(digit);
      const childNode = node.children[i];
      if (childNode === null) {
        break;
      }
      node = childNode;
      maxLength += 1;
    }
    return maxLength;
  }
}