햄버거 만들기 (연습문제)

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

프로그래머스

 

풀이

import java.util.Stack;

class Solution {
    public int solution(int[] ingredient) {
        Stack<Integer> stack = new Stack<>();
        int cnt = 0;

        for (int num : ingredient) {
            stack.add(num);

            if (stack.size() >= 4 && stack.peek() == 1) {
                int lastIdx = stack.size() - 1;

                if (stack.get(lastIdx - 3) == 1
                        && stack.get(lastIdx - 2) == 2
                        && stack.get(lastIdx - 1) == 3
                        && stack.get(lastIdx) == 1) {
                    cnt++;

                    for (int i = 0; i < 4; i++) {
                        stack.pop();
                    }
                }
            }
        }

        return cnt;
    }
}