[백준 10828] 스택

https://www.acmicpc.net/problem/10828

10828번: 스택

 

문제

기본문제. 명령어를 입력받을 때 if를 쓰거나 swich문을 쓰거나

 

import java.util.Scanner;
class stack{
	public static int[] stack=new int[10000];
	public static int pointer=-1;
	public static void push(int n) {
		if(pointer>=stack.length)
			System.out.println("overflow");
		else
			stack[++pointer]=n;
	}
	public static int pop() {
		if(pointer==-1) {
			return -1;
		}
		else
			return stack[pointer--];
	}
	public static int size() {
		return pointer+1;
	}
	public static int empty() {
		if(pointer==-1)
			return 1;
		else 
			return 0;
	}
	public static int top() {
		if(pointer==-1) {
			return -1;
		}
		else
			return stack[pointer];
	}
}
public class Main {
	
	
	public static void main(String[] args) {
		Scanner in=new Scanner(System.in);
		int N=in.nextInt();
		for(int i=0;i<N;i++) {
			String c=in.next();
			switch(c) {
			case "push":
				int n=in.nextInt();
				stack.push(n);
				break;
			case "pop":
				System.out.println(stack.pop());
				break;
			case "empty":
				System.out.println(stack.empty());
				break;
			case "size":
				System.out.println(stack.size());
				break;
			case "top":
				System.out.println(stack.top());
				break;
			}
		}
	}
}

package stack;

import java.util.ArrayList;
import java.util.Scanner;

class Stack{
	int[] stack;
	int pointer;
	public Stack(int num) {
		stack=new int[num];
		this.pointer=-1;
	}
	public void push(int num) {
		pointer++;
		stack[pointer]=num;
	}
	public int pop() {
		if(pointer<0) {
			return -1;
		}
		return stack[pointer--];
	}
	public int size() {
		return pointer+1;
	}
	public int empty() {
		if(pointer<0) {
			return 1;
		}
		else {
			return 0;
		}
	}
	public int top() {
		if(pointer<0) {
			return -1;
		}
		return stack[pointer];
	}
}
public class Main{
	public static void main(String[] args) {
		Scanner in=new Scanner(System.in);
		int N=in.nextInt();
		
		Stack stack=new Stack(10000);
		
		for(int i=0;i<N;i++) {
			String command=in.next();
			if(command.equals("push")) {
				int num=in.nextInt();
				stack.push(num);
			}
			else if(command.equals("pop")) {
				System.out.println(stack.pop());
			}
			else if(command.equals("size")) {
				System.out.println(stack.size());
			}
			else if(command.equals("empty")) {
				System.out.println(stack.empty());
			}
			else if(command.equals("top")) {
				System.out.println(stack.top());
			}
			else {
				System.out.println("다시풀어라~~");
			}
		}
	}
}