hello-algo/zh-hant/codes/ruby/chapter_hashing/hash_map_chaining.rb

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=begin
File: hash_map_chaining.rb
Created Time: 2024-04-13
Author: Xuan Khoa Tu Nguyen (ngxktuzkai2000@gmail.com)
=end
require_relative './array_hash_map'
### 鍵式位址雜湊表 ###
class HashMapChaining
### 建構子 ###
def initialize
@size = 0 # 鍵值對數量
@capacity = 4 # 雜湊表容量
@load_thres = 2.0 / 3.0 # 觸發擴容的負載因子閾值
@extend_ratio = 2 # 擴容倍數
@buckets = Array.new(@capacity) { [] } # 桶陣列
end
### 雜湊函式 ###
def hash_func(key)
key % @capacity
end
### 負載因子 ###
def load_factor
@size / @capacity
end
### 查詢操作 ###
def get(key)
index = hash_func(key)
bucket = @buckets[index]
# 走訪桶,若找到 key ,則返回對應 val
for pair in bucket
return pair.val if pair.key == key
end
# 若未找到 key , 則返回 nil
nil
end
### 新增操作 ###
def put(key, val)
# 當負載因子超過閾值時,執行擴容
extend if load_factor > @load_thres
index = hash_func(key)
bucket = @buckets[index]
# 走訪桶,若遇到指定 key ,則更新對應 val 並返回
for pair in bucket
if pair.key == key
pair.val = val
return
end
end
# 若無該 key ,則將鍵值對新增至尾部
pair = Pair.new(key, val)
bucket << pair
@size += 1
end
### 刪除操作 ###
def remove(key)
index = hash_func(key)
bucket = @buckets[index]
# 走訪桶,從中刪除鍵值對
for pair in bucket
if pair.key == key
bucket.delete(pair)
@size -= 1
break
end
end
end
### 擴容雜湊表 ###
def extend
# 暫存原雜湊表
buckets = @buckets
# 初始化擴容後的新雜湊表
@capacity *= @extend_ratio
@buckets = Array.new(@capacity) { [] }
@size = 0
# 將鍵值對從原雜湊表搬運至新雜湊表
for bucket in buckets
for pair in bucket
put(pair.key, pair.val)
end
end
end
### 列印雜湊表 ###
def print
for bucket in @buckets
res = []
for pair in bucket
res << "#{pair.key} -> #{pair.val}"
end
pp res
end
end
end
### Driver Code ###
if __FILE__ == $0
### 初始化雜湊表
hashmap = HashMapChaining.new
# 新增操作
# 在雜湊表中新增鍵值對 (key, value)
hashmap.put(12836, "小哈")
hashmap.put(15937, "小囉")
hashmap.put(16750, "小算")
hashmap.put(13276, "小法")
hashmap.put(10583, "小鴨")
puts "\n新增完成後,雜湊表為\n[Key1 -> Value1, Key2 -> Value2, ...]"
hashmap.print
# 查詢操作
# 向雜湊表中輸入鍵 key ,得到值 value
name = hashmap.get(13276)
puts "\n輸入學號 13276 ,查詢到姓名 #{name}"
# 刪除操作
# 在雜湊表中刪除鍵值對 (key, value)
hashmap.remove(12836)
puts "\n刪除 12836 後,雜湊表為\n[Key1 -> Value1, Key2 -> Value2, ...]"
hashmap.print
end