Java 10828 스택

풀이 :

스택을 구현할 클래스를 만들어 int형 배열을 생성한 뒤 기능들을 구현하였습니다.

 

 

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {

    static class Stack {
        private int n = 0;
        private int[] stack;

        public Stack(int size){
            stack = new int[size+1];
        }
        public void push (int x){
            stack[n+1] = x;
            n++;
        }
        public int pop(){
            if(n == 0){
                return -1;
            }else {
                int a = stack[n];
                n--;
                return a;
            }
        }
        public int size(){
            return n;
        }
        public int empty(){
            return n == 0? 1 : 0;
        }

        public int top(){
            return n == 0? -1 : stack[n];
        }
    }

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());

        StringTokenizer st;
        Stack stack = new Stack(n);

        for(int i = 0; i < n; i++){
            st = new StringTokenizer(br.readLine()," ");

            String str = st.nextToken();
            switch (str){
                case "push":
                    int num = Integer.parseInt(st.nextToken());
                    stack.push(num);
                    break;
                case "pop":
                    int pop = stack.pop();
                    System.out.println(pop);
                    break;
                case "size":
                    int size = stack.size();
                    System.out.println(size);
                    break;
                case "empty":
                    int empty = stack.empty();
                    System.out.println(empty);
                    break;
                case "top":
                    int top = stack.top();
                    System.out.println(top);
                    break;
                default:
                    break;
            }
        }
    }
}