_1670.java

packagecom.fishercoder.solutions.secondthousand;

importjava.util.ArrayList;
importjava.util.List;

publicclass_1670 {
publicstaticclassSolution1 {
/*
 * This is a brute force approach.
 * TODO: use two Deques to implement a solution.
 */
publicstaticclassFrontMiddleBackQueue {
List<Integer> list;

publicFrontMiddleBackQueue() {
list = newArrayList<>();
 }

publicvoidpushFront(intval) {
list.add(0, val);
 }

publicvoidpushMiddle(intval) {
list.add(list.size() / 2, val);
 }

publicvoidpushBack(intval) {
list.add(val);
 }

publicintpopFront() {
if (list.size() > 0) {
returnlist.remove(0);
 }
return -1;
 }

publicintpopMiddle() {
if (list.size() > 0) {
returnlist.remove(
list.size() % 2 == 0 ? list.size() / 2 - 1 : list.size() / 2);
 }
return -1;
 }

publicintpopBack() {
if (list.size() > 0) {
returnlist.remove(list.size() - 1);
 }
return -1;
 }
 }
 }
}