백준 10828 - 스택 구현

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {

    public static void main(String[] args) throws Exception{
       
        BufferedReader s = new BufferedReader(new InputStreamReader(System.in));
        MSt ms  = new MSt();

        int input = Integer.valueOf(s.readLine());
        String[] temp;
        int result=0;

        while(input-- > 0){

            temp = s.readLine().split(" ");

           switch (temp[0]){
               case "push": ms.push(Integer.valueOf(temp[1]));
                            break;
               case "pop" : result=ms.pop();
                            System.out.println(result);
                            break;
               case "size" : result=ms.size();
                             System.out.println(result);
                             break;
               case "empty" : result=ms.empty();
                              System.out.println(result);
                              break;
               case "top"   : result=ms.top();
                              System.out.println(result);
                              break;
           }

        }

    }

}
class MSt {
    private int[] arr;
    private int size=0;
    MSt(){
        this(10);
    }
    MSt(int n){
        this.arr = new int[n];
    }

   public void push(int n){
        if(size>=arr.length) ensureSize(); //arr.length-1까지만 통과

        arr[size++] = n;
    }
    public int pop(){
        if(empty()==1) return -1;
        int rint = arr[size-1];
     //   if(rint == 0) return -1;

        arr[size-1]=0;
        size--;

        return rint;
    }
    public int size(){
        return this.size;
    }
   public int empty(){
        if(size==0)return 1;
        return 0;
    }
   public int top(){
        if(size ==0) return -1;
        return arr[size-1];
    }
   private void ensureSize(){
        int[] temp = new int[arr.length+6];
        System.arraycopy(arr,0,temp,0,arr.length);
        arr = temp;
    }
}

 

스택 자료구조를 구현하는 문제이다.