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129 lines
2.9 KiB
129 lines
2.9 KiB
=begin
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File: hash_map_chaining.rb
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Created Time: 2024-04-13
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Author: Xuan Khoa Tu Nguyen (ngxktuzkai2000@gmail.com)
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=end
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require_relative './array_hash_map'
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### 键式地址哈希表 ###
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class HashMapChaining
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### 构造方法 ###
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def initialize
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@size = 0 # 键值对数量
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@capacity = 4 # 哈希表容量
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@load_thres = 2.0 / 3.0 # 触发扩容的负载因子阈值
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@extend_ratio = 2 # 扩容倍数
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@buckets = Array.new(@capacity) { [] } # 桶数组
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end
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### 哈希函数 ###
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def hash_func(key)
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key % @capacity
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end
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### 负载因子 ###
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def load_factor
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@size / @capacity
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end
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### 查询操作 ###
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def get(key)
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index = hash_func(key)
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bucket = @buckets[index]
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# 遍历桶，若找到 key ，则返回对应 val
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for pair in bucket
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return pair.val if pair.key == key
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end
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# 若未找到 key , 则返回 nil
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nil
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end
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### 添加操作 ###
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def put(key, val)
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# 当负载因子超过阈值时，执行扩容
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extend if load_factor > @load_thres
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index = hash_func(key)
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bucket = @buckets[index]
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# 遍历桶，若遇到指定 key ，则更新对应 val 并返回
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for pair in bucket
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if pair.key == key
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pair.val = val
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return
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end
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end
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# 若无该 key ，则将键值对添加至尾部
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pair = Pair.new(key, val)
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bucket << pair
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@size += 1
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end
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### 删除操作 ###
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def remove(key)
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index = hash_func(key)
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bucket = @buckets[index]
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# 遍历桶，从中删除键值对
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for pair in bucket
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if pair.key == key
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bucket.delete(pair)
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@size -= 1
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break
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end
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end
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end
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### 扩容哈希表 ###
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def extend
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# 暫存原哈希表
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buckets = @buckets
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# 初始化扩容后的新哈希表
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@capacity *= @extend_ratio
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@buckets = Array.new(@capacity) { [] }
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@size = 0
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# 将键值对从原哈希表搬运至新哈希表
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for bucket in buckets
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for pair in bucket
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put(pair.key, pair.val)
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end
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end
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end
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### 打印哈希表 ###
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def print
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for bucket in @buckets
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res = []
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for pair in bucket
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res << "#{pair.key} -> #{pair.val}"
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end
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pp res
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end
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end
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end
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### Driver Code ###
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if __FILE__ == $0
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### 初始化哈希表
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hashmap = HashMapChaining.new
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# 添加操作
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# 在哈希表中添加键值对 (key, value)
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hashmap.put(12836, "小哈")
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hashmap.put(15937, "小啰")
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hashmap.put(16750, "小算")
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hashmap.put(13276, "小法")
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hashmap.put(10583, "小鸭")
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puts "\n添加完成后，哈希表为\n[Key1 -> Value1, Key2 -> Value2, ...]"
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hashmap.print
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# 查询操作
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# 向哈希表中输入键 key ，得到值 value
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name = hashmap.get(13276)
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puts "\n输入学号 13276 ，查询到姓名 #{name}"
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# 删除操作
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# 在哈希表中删除键值对 (key, value)
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hashmap.remove(12836)
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puts "\n删除 12836 后，哈希表为\n[Key1 -> Value1, Key2 -> Value2, ...]"
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hashmap.print
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end
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