[BOJ] 10866 덱 / C++

https://www.acmicpc.net/problem/10866

10866번: 덱

 

#include <iostream>
#include <string>
#define DEQUE_SIZE	10000

using namespace std;

int N; // 명령의 수 (1<= <= 10000)
string cmd;
int input_data;

int front_ptr = 0, back_ptr = 0;
int deque[DEQUE_SIZE] = { 0, }; // index: 0 ~ 9999

int size() {
	return (front_ptr - back_ptr + DEQUE_SIZE) % DEQUE_SIZE;
}

int empty() {
	if (front_ptr == back_ptr) return 1;
	else return 0;
}

void push_front(int num) {
	if (size() != DEQUE_SIZE) { // NOT FULL
		deque[front_ptr] = num;
		front_ptr = (front_ptr + 1) % DEQUE_SIZE;
	}
}

void push_back(int num) {
	if (size() != DEQUE_SIZE) { // NOT FULL
		back_ptr = (back_ptr - 1 + DEQUE_SIZE) % DEQUE_SIZE;
		deque[back_ptr] = num;
	}
}

int pop_front() {
	if (empty()) return -1;
	int num = deque[(front_ptr - 1 + DEQUE_SIZE) % DEQUE_SIZE];
	front_ptr = (front_ptr - 1 + DEQUE_SIZE) % DEQUE_SIZE;
	return num;
}

int pop_back() {
	if (empty()) return -1;
	int num = deque[back_ptr];
	back_ptr = (back_ptr + 1) % DEQUE_SIZE;
	return num;
}

int front() {
	if (empty()) return -1;
	else return deque[(front_ptr - 1 + DEQUE_SIZE) % DEQUE_SIZE];
}

int back() {
	if (empty()) return -1;
	else return deque[back_ptr];
}

int main(void)
{
	cin >> N;
	
	while (N--) {
		cin >> cmd;
		if (cmd == "push_front") {
			cin >> input_data;
			push_front(input_data);
		}
		else if (cmd == "push_back") {
			cin >> input_data;
			push_back(input_data);
		}
		else if (cmd == "pop_front") {
			int num = pop_front();
			cout << num << "\n";
		}
		else if (cmd == "pop_back") {
			int num = pop_back();
			cout << num << "\n";
		}
		else if (cmd == "size") {
			int deque_size = size();
			cout << deque_size << "\n";
		}
		else if (cmd == "empty") {
			int is_empty = empty();
			cout << is_empty << "\n";
		}
		else if (cmd == "front") {
			int num = front();
			cout << num << "\n";
		}
		else if (cmd == "back") {
			int num = back();
			cout << num << "\n";
		}
	}

	return 0;
}

 

머리 터지는줄 알았네...

원형큐라고 생각하고 그림 그려가면서 했더니 이해 됨