햄버거 만들기

export function makingHamburger(ingredients: number[]) {
  let answer = 0;
  const stack: number[] = [];
 
  const isMakable = () => {
    return 4 <= stack.length && stack.slice(-4).join('') === '1231';
  };
 
  for (const ingredient of ingredients) {
    stack.push(ingredient);
    if (isMakable()) {
      stack.splice(-4, 4);
      answer += 1;
    }
  }
 
  return answer;
}