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hello-algo/codes/csharp/chapter_stack_and_queue/array_deque.cs

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/**
* File: array_deque.cs
* Created Time: 2023-03-08
* Author: hpstory (hpstory1024@163.com)
*/
namespace hello_algo.chapter_stack_and_queue;
/* 基于环形数组实现的双向队列 */
public class ArrayDeque {
int[] nums; // 用于存储双向队列元素的数组
int front; // 队首指针,指向队首元素
int queSize; // 双向队列长度
/* 构造方法 */
public ArrayDeque(int capacity) {
nums = new int[capacity];
front = queSize = 0;
}
/* 获取双向队列的容量 */
int Capacity() {
return nums.Length;
}
/* 获取双向队列的长度 */
public int Size() {
return queSize;
}
/* 判断双向队列是否为空 */
public bool IsEmpty() {
return queSize == 0;
}
/* 计算环形数组索引 */
int Index(int i) {
// 通过取余操作实现数组首尾相连
// 当 i 越过数组尾部后,回到头部
// 当 i 越过数组头部后,回到尾部
return (i + Capacity()) % Capacity();
}
/* 队首入队 */
public void PushFirst(int num) {
if (queSize == Capacity()) {
Console.WriteLine("双向队列已满");
return;
}
// 队首指针向左移动一位
// 通过取余操作实现 front 越过数组头部后回到尾部
front = Index(front - 1);
// 将 num 添加至队首
nums[front] = num;
queSize++;
}
/* 队尾入队 */
public void PushLast(int num) {
if (queSize == Capacity()) {
Console.WriteLine("双向队列已满");
return;
}
// 计算队尾指针,指向队尾索引 + 1
int rear = Index(front + queSize);
// 将 num 添加至队尾
nums[rear] = num;
queSize++;
}
/* 队首出队 */
public int PopFirst() {
int num = PeekFirst();
// 队首指针向后移动一位
front = Index(front + 1);
queSize--;
return num;
}
/* 队尾出队 */
public int PopLast() {
int num = PeekLast();
queSize--;
return num;
}
/* 访问队首元素 */
public int PeekFirst() {
if (IsEmpty()) {
throw new InvalidOperationException();
}
return nums[front];
}
/* 访问队尾元素 */
public int PeekLast() {
if (IsEmpty()) {
throw new InvalidOperationException();
}
// 计算尾元素索引
int last = Index(front + queSize - 1);
return nums[last];
}
/* 返回数组用于打印 */
public int[] ToArray() {
// 仅转换有效长度范围内的列表元素
int[] res = new int[queSize];
for (int i = 0, j = front; i < queSize; i++, j++) {
res[i] = nums[Index(j)];
}
return res;
}
}
public class array_deque {
[Test]
public void Test() {
/* 初始化双向队列 */
ArrayDeque deque = new(10);
deque.PushLast(3);
deque.PushLast(2);
deque.PushLast(5);
Console.WriteLine("双向队列 deque = " + string.Join(" ", deque.ToArray()));
/* 访问元素 */
int peekFirst = deque.PeekFirst();
Console.WriteLine("队首元素 peekFirst = " + peekFirst);
int peekLast = deque.PeekLast();
Console.WriteLine("队尾元素 peekLast = " + peekLast);
/* 元素入队 */
deque.PushLast(4);
Console.WriteLine("元素 4 队尾入队后 deque = " + string.Join(" ", deque.ToArray()));
deque.PushFirst(1);
Console.WriteLine("元素 1 队首入队后 deque = " + string.Join(" ", deque.ToArray()));
/* 元素出队 */
int popLast = deque.PopLast();
Console.WriteLine("队尾出队元素 = " + popLast + ",队尾出队后 deque = " + string.Join(" ", deque.ToArray()));
int popFirst = deque.PopFirst();
Console.WriteLine("队首出队元素 = " + popFirst + ",队首出队后 deque = " + string.Join(" ", deque.ToArray()));
/* 获取双向队列的长度 */
int size = deque.Size();
Console.WriteLine("双向队列长度 size = " + size);
/* 判断双向队列是否为空 */
bool isEmpty = deque.IsEmpty();
Console.WriteLine("双向队列是否为空 = " + isEmpty);
}
}