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145 lines
3.0 KiB
145 lines
3.0 KiB
=begin
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File: array_deque.rb
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Created Time: 2024-04-05
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Author: Xuan Khoa Tu Nguyen (ngxktuzkai2000@gmail.com)
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=end
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### 基于环形数组实现的双向队列 ###
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class ArrayDeque
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### 获取双向队列的长度 ###
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attr_reader :size
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### 构造方法 ###
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def initialize(capacity)
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@nums = Array.new(capacity, 0)
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@front = 0
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@size = 0
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end
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### 获取双向队列的容量 ###
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def capacity
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@nums.length
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end
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### 判断双向队列是否为空 ###
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def is_empty?
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size.zero?
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end
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### 队首入队 ###
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def push_first(num)
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if size == capacity
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puts '双向队列已满'
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return
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end
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# 队首指针向左移动一位
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# 通过取余操作实现 front 越过数组头部后回到尾部
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@front = index(@front - 1)
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# 将 num 添加至队首
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@nums[@front] = num
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@size += 1
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end
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### 队尾入队 ###
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def push_last(num)
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if size == capacity
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puts '双向队列已满'
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return
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end
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# 计算队尾指针，指向队尾索引 + 1
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rear = index(@front + size)
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# 将 num 添加至队尾
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@nums[rear] = num
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@size += 1
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end
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### 队首出队 ###
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def pop_first
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num = peek_first
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# 队首指针向后移动一位
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@front = index(@front + 1)
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@size -= 1
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num
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end
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### 队尾出队 ###
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def pop_last
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num = peek_last
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@size -= 1
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num
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end
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### 访问队首元素 ###
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def peek_first
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raise IndexError, '双向队列为空' if is_empty?
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@nums[@front]
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end
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### 访问队尾元素 ###
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def peek_last
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raise IndexError, '双向队列为空' if is_empty?
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# 计算尾元素索引
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last = index(@front + size - 1)
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@nums[last]
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end
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### 返回数组用于打印 ###
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def to_array
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# 仅转换有效长度范围内的列表元素
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res = []
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for i in 0...size
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res << @nums[index(@front + i)]
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end
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res
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end
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private
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### 计算环形数组索引 ###
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def index(i)
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# 通过取余操作实现数组首尾相连
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# 当 i 越过数组尾部后，回到头部
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# 当 i 越过数组头部后，回到尾部
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(i + capacity) % capacity
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end
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end
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### Driver Code ###
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# 初始化双向队列
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deque = ArrayDeque.new(10)
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deque.push_last(3)
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deque.push_last(2)
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deque.push_last(5)
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puts "双向队列 deque = #{deque.to_array}"
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# 访问元素
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peek_first = deque.peek_first
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puts "队首元素 peek_first = #{peek_first}"
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peek_last = deque.peek_last
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puts "队尾元素 peek_last = #{peek_last}"
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# 元素入队
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deque.push_last(4)
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puts "元素 4 队尾入队后 deque = #{deque.to_array}"
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deque.push_first(1)
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puts "元素 1 队尾入队后 deque = #{deque.to_array}"
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# 元素出队
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pop_last = deque.pop_last
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puts "队尾出队元素 = #{pop_last}，队尾出队后 deque = #{deque.to_array}"
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pop_first = deque.pop_first
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puts "队尾出队元素 = #{pop_first}，队尾出队后 deque = #{deque.to_array}"
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# 获取双向队列的长度
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size = deque.size
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puts "双向队列长度 size = #{size}"
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# 判断双向队列是否为空
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is_empty = deque.is_empty?
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puts "双向队列是否为空 = #{is_empty}"
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