[Java] 백준 10866번: 덱

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

public class BOJ_10866_덱 {
	static class MyDeque {
		Integer[] deqArray;
		int size;
		
		public MyDeque() {
			deqArray = null;
			this.size = 0;
		}
		
		public void push_front(int num) {
			Integer[] tmp = new Integer[this.size+1];
			tmp[0] = num;
			
			for(int i=0; i<this.size; ++i) {
				tmp[i+1] = deqArray[i];
			}
			
			deqArray = tmp;
			++this.size;
		}
		public void push_back(int num) {
			Integer[] tmp = new Integer[this.size+1];
			tmp[this.size] = num;
			
			for(int i=0; i<this.size; ++i) {
				tmp[i] = deqArray[i];
			}
			
			deqArray = tmp;	
			++this.size;
		}
		public int pop_front() {
			if(this.size == 0) return -1;
			
			Integer[] tmp = new Integer[this.size-1];
			int ret = deqArray[0];

			for(int i=1; i<this.size; ++i) {
				tmp[i-1] = deqArray[i];
			}
			
			deqArray = tmp;
			--this.size;
			
			return ret;
		}
		public int pop_back() {
			if(this.size == 0) return -1;
			
			Integer[] tmp = new Integer[this.size-1];
			int ret = deqArray[this.size-1];

			for(int i=0; i<deqArray.length-1; ++i) {
				tmp[i] = deqArray[i];
			}
			
			deqArray = tmp;
			--this.size;
			
			return ret;
		}
		public int size() {
			return this.size;
		}
		public int empty() {
			return size==0 ? 1 : 0;
		}
		public int front() {
			return size==0 ? -1 : deqArray[0];
		}
		public int back() {
			return size==0 ? -1 : deqArray[size-1];
		}
	}
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int T = Integer.parseInt(br.readLine());
		MyDeque deque = new MyDeque();
		StringBuilder sb = new StringBuilder();
		
		for(int i=0; i<T; ++i) {
			StringTokenizer st = new StringTokenizer(br.readLine(), " ");
			
			String command = st.nextToken();
			
			switch(command) {
				case "push_back": deque.push_back(Integer.parseInt(st.nextToken())); break;
				case "push_front": deque.push_front(Integer.parseInt(st.nextToken())); break;
				case "pop_back": sb.append(deque.pop_back()).append('\n'); break;
				case "pop_front": sb.append(deque.pop_front()).append('\n'); break;
				case "size": sb.append(deque.size()).append('\n'); break;
				case "empty": sb.append(deque.empty()).append('\n'); break;
				case "front": sb.append(deque.front()).append('\n'); break;
				case "back": sb.append(deque.back()).append('\n'); break;
			}
		}

		System.out.println(sb);
	}

}