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Queue641.java
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package queue;
import java.util.Stack;
/**
* @ProjectName: leetcode
* @Package: PACKAGE_NAME
* @ClassName: Queue641
* @Author: markey
* @Description:
* @Date: 2019/10/6 11:23
* @Version: 1.0
*/
public class Queue641 {
public static void main(String[] args) {
MyCircularDeque2 circularDeque = new MyCircularDeque2(3); // 设置容量大小为3
System.out.println(circularDeque.insertLast(1));// 返回 true
System.out.println(circularDeque.insertLast(2));// 返回 true
System.out.println(circularDeque.insertFront(3));// 返回 true
System.out.println(circularDeque.insertFront(4));// 已经满了，返回 false
System.out.println(circularDeque.getRear());// 返回 2
System.out.println(circularDeque.isFull());// 返回 true
System.out.println(circularDeque.deleteLast());// 返回 true
System.out.println(circularDeque.insertFront(4));// 返回 true
System.out.println(circularDeque.getFront());// 返回 4
}
/**
* 使用循环数组实现，
* 记录队列的头和尾指针
* 执行用时 :64 ms, 在所有 Java 提交中击败了92.38%的用户
* 内存消耗 :38.6 MB, 在所有 Java 提交中击败了98.31%的用户
*/
static class MyCircularDeque2 {
int[] array;
int head, tail, size, count;
/** Initialize your data structure here. Set the size of the deque to be k. */
public MyCircularDeque2(int k) {
array = new int[k];
head = 0;
tail = 0;
size = k;
count = 0;
}
/** Adds an item at the front of Deque. Return true if the operation is successful. */
public boolean insertFront(int value) {
if (isFull()) {
return false;
}
head = (head + size - 1) % size;
array[head] = value;
count ++;
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;
}
array[tail] = value;
tail = (tail + 1) % size;
count ++;
return true;
}
/** Deletes an item from the front of Deque. Return true if the operation is successful. */
public boolean deleteFront() {
if (this.isEmpty()) {
return false;
}
head++;
if (head >= size) head -= size;
count --;
return true;
}
/** Deletes an item from the rear of Deque. Return true if the operation is successful. */
public boolean deleteLast() {
if (this.isEmpty()) {
return false;
}
tail--;
if (tail < 0) tail += size;
count --;
return true;
}
/** Get the front item from the deque. */
public int getFront() {
if (this.isEmpty()) {
return -1;
}
return array[head];
}
/** Get the last item from the deque. */
public int getRear() {
if (this.isEmpty()) {
return -1;
}
if (tail - 1 < 0) {
return array[tail + size - 1];
}
return array[tail - 1];
}
/** Checks whether the circular deque is empty or not. */
public boolean isEmpty() {
return count == 0;
}
/** Checks whether the circular deque is full or not. */
public boolean isFull() {
return count == size;
}
}
/**
* 使用双栈实现双端队列
* 一个栈的栈顶是头部元素，另一个栈的栈顶是尾部元素
* 执行用时 :63 ms, 在所有 Java 提交中击败了93.81%的用户
* 内存消耗 :37.6 MB, 在所有 Java 提交中击败了98.31%的用户
*/
static class MyCircularDeque {
Stack<Integer> head;
Stack<Integer> tail;
int size;
/** Initialize your data structure here. Set the size of the deque to be k. */
public MyCircularDeque(int k) {
head = new Stack<>();
tail = new Stack<>();
size = k;
}
/** Adds an item at the front of Deque. Return true if the operation is successful. */
public boolean insertFront(int value) {
if (head.size() + tail.size() < size) {
head.push(value);
return true;
}
return false;
}
/** Adds an item at the rear of Deque. Return true if the operation is successful. */
public boolean insertLast(int value) {
if (head.size() + tail.size() < size) {
tail.push(value);
return true;
}
return false;
}
/** Deletes an item from the front of Deque. Return true if the operation is successful. */
public boolean deleteFront() {
if (head.isEmpty()) {
while (!tail.isEmpty()) {
head.push(tail.pop());
}
}
if (head.isEmpty()) {
return false;
} else {
head.pop();
return true;
}
}
/** Deletes an item from the rear of Deque. Return true if the operation is successful. */
public boolean deleteLast() {
if (tail.isEmpty()) {
while (!head.isEmpty()) {
tail.push(head.pop());
}
}
if (tail.isEmpty()) {
return false;
} else {
tail.pop();
return true;
}
}
/** Get the front item from the deque. */
public int getFront() {
if (head.isEmpty()) {
while (!tail.isEmpty()) {
head.push(tail.pop());
}
}
if (head.isEmpty()) {
return -1;
} else {
return head.peek();
}
}
/** Get the last item from the deque. */
public int getRear() {
if (tail.isEmpty()) {
while (!head.isEmpty()) {
tail.push(head.pop());
}
}
if (tail.isEmpty()) {
return -1;
} else {
return tail.peek();
}
}
/** Checks whether the circular deque is empty or not. */
public boolean isEmpty() {
return head.isEmpty() && tail.isEmpty();
}
/** Checks whether the circular deque is full or not. */
public boolean isFull() {
return head.size() + tail.size() >= size;
}
}
/**
* 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();
*/
}