[프로그래머스] lv1 햄버거 만들기

실패

function solution(ingredient) {
    var answer = 0;
    
    for(let index = 0; index <= ingredient.length; index++){
        const first = ingredient[index], second = ingredient[index+1], 
          third = ingredient[index+2], fourth = ingredient[index+3];
        
        if(first + 1 === second && second + 1 === third && first === fourth){
            ingredient.splice(first, 4)
            answer++;
        }
    }
    
    return answer;
}

while 문을 써야하나? 고민했지만 실패.

 

통과

/*
* 햄버거 만들기
* 빵 – 야채 – 고기 - 빵 <=> 1-2-3-1
*/
function solution(ingredient) {
    var answer = 0;
 
    let stack = [];
    for(let index = 0; index <= ingredient.length; index++){
       stack.push(ingredient[index]);
        
        if(stack.length > 3){
            const isHamburger = stack.slice(-4).join('') === '1231';
            if(isHamburger){
               stack.splice(-4);
                answer++;
            }
        }
        
    }
    
    return answer;
}