[BaekJoon] 10828번 스택 문제 풀이 (Success)

10828번: 스택

 

☕Language: Java

 

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.Stack;
import java.util.StringTokenizer;
 
public class Main {
 
    public static void main(String[] args) throws IOException {
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 
        int cnt = Integer.parseInt(br.readLine());
 
        Stack<String> stack = new Stack<>();
 
        StringBuffer sb = new StringBuffer();
 
        while (cnt-- > 0) {
            StringTokenizer st = new StringTokenizer(br.readLine(), " ");
 
            switch (st.nextToken()) {
            case "push":
                stack.push(st.nextToken());
                break;
            case "top":
                if (!stack.isEmpty()) {
                    sb.append(stack.lastElement() + "\n");
                } else {
                    sb.append("-1\n");
                }
                break;
            case "size":
                sb.append(stack.size() + "\n");
                break;
            case "empty":
                sb.append((stack.isEmpty() ? "1" : "0") + "\n");
                break;
            case "pop":
                if (!stack.isEmpty()) {
                    sb.append(stack.lastElement() + "\n");
                    stack.pop();
                } else {
                    sb.append("-1\n");
                }
                break;
            }
 
        }
 
        bw.write(sb + "");
 
        bw.flush();
        bw.close();
 
    }
 
}
 

🤔 해설

1. case "push":

    - 입력값이 push일 경우, 입력값을 추가로 받음

 

😮 이 외의 풀이

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.StringTokenizer;
 
public class Main {
 
    static int[] stack;
    static int location = 0;
 
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
 
        StringBuilder sb = new StringBuilder();
 
        int N = Integer.valueOf(br.readLine());
 
        stack = new int[N];
 
        StringTokenizer st;
 
        while (N-- > 0) {
            st = new StringTokenizer(br.readLine(), " ");
 
            switch (st.nextToken()) {
            case "push":
                push(Integer.parseInt(st.nextToken()));
                break;
            case "pop":
                sb.append(pop()).append("\n");
                break;
            case "size":
                sb.append(size()).append("\n");
                break;
            case "empty":
                sb.append(empty()).append("\n");
                break;
            case "top":
                sb.append(top()).append("\n");
                break;
            }
 
        }
 
        bw.append(sb.toString());
 
        bw.flush();
        bw.close();
    }
 
    public static void push(int i) {
        stack[location] = i;
        location++;
    }
 
    public static int pop() {
        if (location == 0) {
            return -1;
        } else {
            int result = stack[location - 1];
            stack[location - 1] = 0;
            location--;
            return result;
        }
    }
 
    public static int size() {
        return location;
    }
 
    public static int empty() {
        return location == 0 ? 1 : 0;
    }
 
    public static int top() {
        return location == 0 ? -1 : stack[location - 1];
    }
 
}
 

1. static int[] stack;

    - int[]로 stack 구현

 

2. static int location = 0;

    - 배열의 위치 반환

 

3. public static void push(int i) { ... }

    - 현재 위치에 입력값 삽입

    - location 위치 오른쪽으로 이동

 

4. public static int pop() { ... }

    - 가장 마지막에 위치한 요소 출력 및 0 대입

    - location 위치 왼쪽으로 이동

 

5. public static int size() { ... }

    - location 출력

 

 

 

🔗 소스 코드
GitHub

 

📚 참고 자료

[백준] 10828번 : 스택 - JAVA [자바]