28일차 (알고리즘: stack 활용)

https://school.programmers.co.kr/learn/courses/30/lessons/133502

프로그래머스

 

처음 시도 코드

function solution(ingredient) {
    var answer = 0;
    let stringIngredient = ingredient.join("")
    let burger = 1231
    
    while(stringIngredient.includes(burger)){
            stringIngredient = stringIngredient.replace(burger, "")
            answer++       
    }
    return answer;
}

문제점: replace를 사용하니 시간 복잡도가 높아져서 시간초과가 발생

 

 

해결 방안: stack 활용

function solution(ingredient) {
    var answer = 0;
    let stack = []
    
    ingredient.forEach((item)=>{
        stack.push(item)
        let stackLength = stack.length
        
        if(stack[stackLength-4] === 1 &&
           stack[stackLength-3] === 2 &&
           stack[stackLength-2] === 3 &&
           stack[stackLength-1] === 1){
            for(let i=0; i<4; i++){
                stack.pop()
            }
            answer++
        }  
    })
    return answer;
}