export function commonChars(a: string, b: string): number {
  if (a.length === 0 || b.length === 0) return 0;

  let commonChars: string[] = [];
  let aTokenized: string[] = tokenizeString(a).map(char => char.toLowerCase());
  let bTokenized: string[] = tokenizeString(b).map(char => char.toLowerCase());
  aTokenized.forEach(char => {
    if (bTokenized.includes(char) && !commonChars.includes(char)) commonChars.push(char);
  });
  return commonChars.length;
}

function tokenizeString(text: string): string[] {
    let res: string[] = [];
    for (let i: number = 0; i < text.length; i++) {
        res.push(text[i]);
    }
    return res;
}