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| class FrontMiddleBackQueue {
private Deque<Integer> leftDeque;
private Deque<Integer> rightDeque;
public FrontMiddleBackQueue() {
this.leftDeque = new LinkedList<>();
this.rightDeque = new LinkedList<>();
}
public void pushFront(int val) {
leftDeque.addFirst(val);
if (leftDeque.size() > rightDeque.size() + 1) {
rightDeque.addFirst(leftDeque.pollLast());
}
}
public void pushMiddle(int val) {
if (leftDeque.size() > rightDeque.size()) {
rightDeque.addFirst(leftDeque.pollLast());
}
leftDeque.addLast(val);
}
public void pushBack(int val) {
rightDeque.addLast(val);
if (rightDeque.size() > leftDeque.size()) {
leftDeque.addLast(rightDeque.pollFirst());
}
}
public int popFront() {
if (leftDeque.isEmpty()) {
return -1;
}
Integer ans = leftDeque.pollFirst();
if (leftDeque.size() < rightDeque.size()) {
leftDeque.addLast(rightDeque.pollFirst());
}
return ans;
}
public int popMiddle() {
if (leftDeque.isEmpty()) {
return -1;
}
Integer ans = leftDeque.pollLast();
if (leftDeque.size() < rightDeque.size()) {
leftDeque.addLast(rightDeque.pollFirst());
}
return ans;
}
public int popBack() {
if (rightDeque.isEmpty()) {
if (leftDeque.isEmpty()) {
return -1;
}
return leftDeque.pollLast();
}
Integer ans = rightDeque.pollLast();
if (leftDeque.size() > rightDeque.size() + 1) {
rightDeque.addFirst(leftDeque.pollLast());
}
return ans;
}
}
/**
* Your FrontMiddleBackQueue object will be instantiated and called as such:
* FrontMiddleBackQueue obj = new FrontMiddleBackQueue();
* obj.pushFront(val);
* obj.pushMiddle(val);
* obj.pushBack(val);
* int param_4 = obj.popFront();
* int param_5 = obj.popMiddle();
* int param_6 = obj.popBack();
*/
|
