题解:
类似的题目为:leetcode622题设计循环队列,622题的 题解 先附上。
本题和622题是一样的,注意的点也在我的题解上有详细的说明,在这里就不重复了。底层依旧是使用数组,以及两个指针front,tail分别标记队首元素和下一个addLast的添加位置。代码如下:
class MyCircularDeque {
private int[] data;
private int front;
private int tail;
/** Initialize your data structure here. Set the size of the deque to be k. */
public MyCircularDeque(int k) {
data = new int[k + 1];
front = 0;
tail = 0;
}
private int getSize(){
if(tail < front){
return data.length - front + tail;
}else{
return tail - front;
}
}
/** Adds an item at the front of Deque. Return true if the operation is successful. */
public boolean insertFront(int value) {
if(isFull()){
return false;
}else{
front = (front + data.length - 1) % data.length;
data[front] = value;
return true;
}
}
/** Adds an item at the rear of Deque. Return true if the operation is successful. */
public boolean insertLast(int value) {
if(isFull()){
return false;
}else{
data[tail] = value;
tail = (tail + 1) % data.length;
return true;
}
}
/** Deletes an item from the front of Deque. Return true if the operation is successful. */
public boolean deleteFront() {
if(getSize() == 0){
return false;
}else{
front = (front + 1) % data.length;
return true;
}
}
/** Deletes an item from the rear of Deque. Return true if the operation is successful. */
public boolean deleteLast() {
if(getSize() == 0){
return false;
}else{
tail = (tail + data.length - 1) % data.length;
return true;
}
}
/** Get the front item from the deque. */
public int getFront() {
if(front == tail){
return -1;
}else{
return data[front];
}
}
/** Get the last item from the deque. */
public int getRear() {
if(front == tail){
return -1;
}else{
return data[(front + getSize() - 1) % data.length];
}
}
/** Checks whether the circular deque is empty or not. */
public boolean isEmpty() {
return front == tail;
}
/** Checks whether the circular deque is full or not. */
public boolean isFull() {
return getSize() == data.length - 1;
}
}
/**
* Your MyCircularDeque object will be instantiated and called as such:
* MyCircularDeque obj = new MyCircularDeque(k);
* boolean param_1 = obj.insertFront(value);
* boolean param_2 = obj.insertLast(value);
* boolean param_3 = obj.deleteFront();
* boolean param_4 = obj.deleteLast();
* int param_5 = obj.getFront();
* int param_6 = obj.getRear();
* boolean param_7 = obj.isEmpty();
* boolean param_8 = obj.isFull();
*/
执行结果如下:
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