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https://github.com/krahets/hello-algo.git
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build
This commit is contained in:
@@ -276,7 +276,20 @@ comments: true
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=== "Ruby"
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```ruby title="bubble_sort.rb"
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[class]{}-[func]{bubble_sort}
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### 泡沫排序 ###
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def bubble_sort(nums)
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n = nums.length
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# 外迴圈:未排序區間為 [0, i]
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for i in (n - 1).downto(1)
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# 內迴圈:將未排序區間 [0, i] 中的最大元素交換至該區間的最右端
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for j in 0...i
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if nums[j] > nums[j + 1]
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# 交換 nums[j] 與 nums[j + 1]
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nums[j], nums[j + 1] = nums[j + 1], nums[j]
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end
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end
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end
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end
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```
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=== "Zig"
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@@ -587,7 +600,25 @@ comments: true
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=== "Ruby"
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```ruby title="bubble_sort.rb"
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[class]{}-[func]{bubble_sort_with_flag}
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### 泡沫排序(標誌最佳化)###
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def bubble_sort_with_flag(nums)
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n = nums.length
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# 外迴圈:未排序區間為 [0, i]
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for i in (n - 1).downto(1)
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flag = false # 初始化標誌位
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# 內迴圈:將未排序區間 [0, i] 中的最大元素交換至該區間的最右端
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for j in 0...i
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if nums[j] > nums[j + 1]
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# 交換 nums[j] 與 nums[j + 1]
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nums[j], nums[j + 1] = nums[j + 1], nums[j]
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flag = true # 記錄交換元素
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end
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end
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break unless flag # 此輪“冒泡”未交換任何元素,直接跳出
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end
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end
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```
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=== "Zig"
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@@ -406,7 +406,35 @@ comments: true
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=== "Ruby"
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```ruby title="bucket_sort.rb"
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[class]{}-[func]{bucket_sort}
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### 桶排序 ###
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def bucket_sort(nums)
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# 初始化 k = n/2 個桶,預期向每個桶分配 2 個元素
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k = nums.length / 2
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buckets = Array.new(k) { [] }
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# 1. 將陣列元素分配到各個桶中
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nums.each do |num|
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# 輸入資料範圍為 [0, 1),使用 num * k 對映到索引範圍 [0, k-1]
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i = (num * k).to_i
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# 將 num 新增進桶 i
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buckets[i] << num
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end
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# 2. 對各個桶執行排序
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buckets.each do |bucket|
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# 使用內建排序函式,也可以替換成其他排序演算法
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bucket.sort!
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end
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# 3. 走訪桶合併結果
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i = 0
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buckets.each do |bucket|
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bucket.each do |num|
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nums[i] = num
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i += 1
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end
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end
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end
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```
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=== "Zig"
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@@ -348,7 +348,25 @@ comments: true
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=== "Ruby"
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```ruby title="counting_sort.rb"
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[class]{}-[func]{counting_sort_naive}
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### 計數排序 ###
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def counting_sort_naive(nums)
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# 簡單實現,無法用於排序物件
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# 1. 統計陣列最大元素 m
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m = 0
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nums.each { |num| m = [m, num].max }
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# 2. 統計各數字的出現次數
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# counter[num] 代表 num 的出現次數
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counter = Array.new(m + 1, 0)
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nums.each { |num| counter[num] += 1 }
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# 3. 走訪 counter ,將各元素填入原陣列 nums
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i = 0
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for num in 0...(m + 1)
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(0...counter[num]).each do
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nums[i] = num
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i += 1
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end
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end
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end
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```
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=== "Zig"
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@@ -854,7 +872,30 @@ $$
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=== "Ruby"
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```ruby title="counting_sort.rb"
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[class]{}-[func]{counting_sort}
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### 計數排序 ###
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def counting_sort(nums)
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# 完整實現,可排序物件,並且是穩定排序
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# 1. 統計陣列最大元素 m
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m = nums.max
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# 2. 統計各數字的出現次數
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# counter[num] 代表 num 的出現次數
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counter = Array.new(m + 1, 0)
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nums.each { |num| counter[num] += 1 }
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# 3. 求 counter 的前綴和,將“出現次數”轉換為“尾索引”
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# 即 counter[num]-1 是 num 在 res 中最後一次出現的索引
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(0...m).each { |i| counter[i + 1] += counter[i] }
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# 4. 倒序走訪 nums, 將各元素填入結果陣列 res
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# 初始化陣列 res 用於記錄結果
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n = nums.length
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res = Array.new(n, 0)
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(n - 1).downto(0).each do |i|
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num = nums[i]
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res[counter[num] - 1] = num # 將 num 放置到對應索引處
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counter[num] -= 1 # 令前綴和自減 1 ,得到下次放置 num 的索引
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end
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# 使用結果陣列 res 覆蓋原陣列 nums
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(0...n).each { |i| nums[i] = res[i] }
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end
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```
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=== "Zig"
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@@ -582,9 +582,38 @@ comments: true
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=== "Ruby"
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```ruby title="heap_sort.rb"
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[class]{}-[func]{sift_down}
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### 堆積的長度為 n ,從節點 i 開始,從頂至底堆積化 ###
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def sift_down(nums, n, i)
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while true
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# 判斷節點 i, l, r 中值最大的節點,記為 ma
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l = 2 * i + 1
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r = 2 * i + 2
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ma = i
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ma = l if l < n && nums[l] > nums[ma]
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ma = r if r < n && nums[r] > nums[ma]
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# 若節點 i 最大或索引 l, r 越界,則無須繼續堆積化,跳出
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break if ma == i
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# 交換兩節點
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nums[i], nums[ma] = nums[ma], nums[i]
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# 迴圈向下堆積化
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i = ma
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end
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end
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[class]{}-[func]{heap_sort}
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### 堆積排序 ###
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def heap_sort(nums)
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# 建堆積操作:堆積化除葉節點以外的其他所有節點
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(nums.length / 2 - 1).downto(0) do |i|
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sift_down(nums, nums.length, i)
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end
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# 從堆積中提取最大元素,迴圈 n-1 輪
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(nums.length - 1).downto(1) do |i|
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# 交換根節點與最右葉節點(交換首元素與尾元素)
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nums[0], nums[i] = nums[i], nums[0]
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# 以根節點為起點,從頂至底進行堆積化
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sift_down(nums, i, 0)
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end
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end
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```
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=== "Zig"
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@@ -630,9 +630,53 @@ comments: true
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=== "Ruby"
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```ruby title="merge_sort.rb"
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[class]{}-[func]{merge}
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### 合併左子陣列和右子陣列 ###
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def merge(nums, left, mid, right)
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# 左子陣列區間為 [left, mid], 右子陣列區間為 [mid+1, right]
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# 建立一個臨時陣列 tmp,用於存放合併後的結果
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tmp = Array.new(right - left + 1, 0)
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# 初始化左子陣列和右子陣列的起始索引
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i, j, k = left, mid + 1, 0
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# 當左右子陣列都還有元素時,進行比較並將較小的元素複製到臨時陣列中
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while i <= mid && j <= right
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if nums[i] <= nums[j]
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tmp[k] = nums[i]
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i += 1
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else
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tmp[k] = nums[j]
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j += 1
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end
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k += 1
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end
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# 將左子陣列和右子陣列的剩餘元素複製到臨時陣列中
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while i <= mid
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tmp[k] = nums[i]
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i += 1
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k += 1
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end
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while j <= right
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tmp[k] = nums[j]
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j += 1
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k += 1
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end
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# 將臨時陣列 tmp 中的元素複製回原陣列 nums 的對應區間
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(0...tmp.length).each do |k|
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nums[left + k] = tmp[k]
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end
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end
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[class]{}-[func]{merge_sort}
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### 合併排序 ###
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def merge_sort(nums, left, right)
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# 終止條件
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# 當子陣列長度為 1 時終止遞迴
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return if left >= right
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# 劃分階段
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mid = (left + right) / 2 # 計算中點
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merge_sort(nums, left, mid) # 遞迴左子陣列
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merge_sort(nums, mid + 1, right) # 遞迴右子陣列
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# 合併階段
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merge(nums, left, mid, right)
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end
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```
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=== "Zig"
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@@ -353,7 +353,24 @@ comments: true
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=== "Ruby"
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```ruby title="quick_sort.rb"
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[class]{QuickSort}-[func]{partition}
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### 哨兵劃分 ###
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def partition(nums, left, right)
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# 以 nums[left] 為基準數
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i, j = left, right
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while i < j
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while i < j && nums[j] >= nums[left]
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j -= 1 # 從右向左找首個小於基準數的元素
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end
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while i < j && nums[i] <= nums[left]
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i += 1 # 從左向右找首個大於基準數的元素
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end
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# 元素交換
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nums[i], nums[j] = nums[j], nums[i]
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end
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# 將基準數交換至兩子陣列的分界線
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nums[i], nums[left] = nums[left], nums[i]
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i # 返回基準數的索引
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end
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```
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=== "Zig"
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@@ -594,7 +611,18 @@ comments: true
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=== "Ruby"
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```ruby title="quick_sort.rb"
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[class]{QuickSort}-[func]{quick_sort}
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### 快速排序類別 ###
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def quick_sort(nums, left, right)
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# 子陣列長度不為 1 時遞迴
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if left < right
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# 哨兵劃分
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pivot = partition(nums, left, right)
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# 遞迴左子陣列、右子陣列
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quick_sort(nums, left, pivot - 1)
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quick_sort(nums, pivot + 1, right)
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end
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nums
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end
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```
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|
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=== "Zig"
|
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@@ -1067,9 +1095,38 @@ comments: true
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=== "Ruby"
|
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```ruby title="quick_sort.rb"
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[class]{QuickSortMedian}-[func]{median_three}
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### 選取三個候選元素的中位數 ###
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def median_three(nums, left, mid, right)
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# 選取三個候選元素的中位數
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_l, _m, _r = nums[left], nums[mid], nums[right]
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# m 在 l 和 r 之間
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return mid if (_l <= _m && _m <= _r) || (_r <= _m && _m <= _l)
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# l 在 m 和 r 之間
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return left if (_m <= _l && _l <= _r) || (_r <= _l && _l <= _m)
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return right
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end
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|
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[class]{QuickSortMedian}-[func]{partition}
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### 哨兵劃分(三數取中值)###
|
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def partition(nums, left, right)
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### 以 nums[left] 為基準數
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med = median_three(nums, left, (left + right) / 2, right)
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# 將中位數交換至陣列最左斷
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nums[left], nums[med] = nums[med], nums[left]
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i, j = left, right
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while i < j
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while i < j && nums[j] >= nums[left]
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j -= 1 # 從右向左找首個小於基準數的元素
|
||||
end
|
||||
while i < j && nums[i] <= nums[left]
|
||||
i += 1 # 從左向右找首個大於基準數的元素
|
||||
end
|
||||
# 元素交換
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nums[i], nums[j] = nums[j], nums[i]
|
||||
end
|
||||
# 將基準數交換至兩子陣列的分界線
|
||||
nums[i], nums[left] = nums[left], nums[i]
|
||||
i # 返回基準數的索引
|
||||
end
|
||||
```
|
||||
|
||||
=== "Zig"
|
||||
@@ -1377,7 +1434,22 @@ comments: true
|
||||
=== "Ruby"
|
||||
|
||||
```ruby title="quick_sort.rb"
|
||||
[class]{QuickSortTailCall}-[func]{quick_sort}
|
||||
### 快速排序(尾遞迴最佳化)###
|
||||
def quick_sort(nums, left, right)
|
||||
# 子陣列長度不為 1 時遞迴
|
||||
while left < right
|
||||
# 哨兵劃分
|
||||
pivot = partition(nums, left, right)
|
||||
# 對兩個子陣列中較短的那個執行快速排序
|
||||
if pivot - left < right - pivot
|
||||
quick_sort(nums, left, pivot - 1)
|
||||
left = pivot + 1 # 剩餘未排序區間為 [pivot + 1, right]
|
||||
else
|
||||
quick_sort(nums, pivot + 1, right)
|
||||
right = pivot - 1 # 剩餘未排序區間為 [left, pivot - 1]
|
||||
end
|
||||
end
|
||||
end
|
||||
```
|
||||
|
||||
=== "Zig"
|
||||
|
||||
@@ -677,11 +677,51 @@ $$
|
||||
=== "Ruby"
|
||||
|
||||
```ruby title="radix_sort.rb"
|
||||
[class]{}-[func]{digit}
|
||||
### 獲取元素 num 的第 k 位,其中 exp = 10^(k-1) ###
|
||||
def digit(num, exp)
|
||||
# 轉入 exp 而非 k 可以避免在此重複執行昂貴的次方計算
|
||||
(num / exp) % 10
|
||||
end
|
||||
|
||||
[class]{}-[func]{counting_sort_digit}
|
||||
### 計數排序(根據 nums 第 k 位排序)###
|
||||
def counting_sort_digit(nums, exp)
|
||||
# 十進位制的位範圍為 0~9 ,因此需要長度為 10 的桶陣列
|
||||
counter = Array.new(10, 0)
|
||||
n = nums.length
|
||||
# 統計 0~9 各數字的出現次數
|
||||
for i in 0...n
|
||||
d = digit(nums[i], exp) # 獲取 nums[i] 第 k 位,記為 d
|
||||
counter[d] += 1 # 統計數字 d 的出現次數
|
||||
end
|
||||
# 求前綴和,將“出現個數”轉換為“陣列索引”
|
||||
(1...10).each { |i| counter[i] += counter[i - 1] }
|
||||
# 倒序走訪,根據桶內統計結果,將各元素填入 res
|
||||
res = Array.new(n, 0)
|
||||
for i in (n - 1).downto(0)
|
||||
d = digit(nums[i], exp)
|
||||
j = counter[d] - 1 # 獲取 d 在陣列中的索引 j
|
||||
res[j] = nums[i] # 將當前元素填入索引 j
|
||||
counter[d] -= 1 # 將 d 的數量減 1
|
||||
end
|
||||
# 使用結果覆蓋原陣列 nums
|
||||
(0...n).each { |i| nums[i] = res[i] }
|
||||
end
|
||||
|
||||
[class]{}-[func]{radix_sort}
|
||||
### 基數排序 ###
|
||||
def radix_sort(nums)
|
||||
# 獲取陣列的最大元素,用於判斷最大位數
|
||||
m = nums.max
|
||||
# 按照從低位到高位的順序走訪
|
||||
exp = 1
|
||||
while exp <= m
|
||||
# 對陣列元素的第 k 位執行計數排序
|
||||
# k = 1 -> exp = 1
|
||||
# k = 2 -> exp = 10
|
||||
# 即 exp = 10^(k-1)
|
||||
counting_sort_digit(nums, exp)
|
||||
exp *= 10
|
||||
end
|
||||
end
|
||||
```
|
||||
|
||||
=== "Zig"
|
||||
|
||||
@@ -306,7 +306,22 @@ comments: true
|
||||
=== "Ruby"
|
||||
|
||||
```ruby title="selection_sort.rb"
|
||||
[class]{}-[func]{selection_sort}
|
||||
### 選擇排序 ###
|
||||
def selection_sort(nums)
|
||||
n = nums.length
|
||||
# 外迴圈:未排序區間為 [i, n-1]
|
||||
for i in 0...(n - 1)
|
||||
# 內迴圈:找到未排序區間內的最小元素
|
||||
k = i
|
||||
for j in (i + 1)...n
|
||||
if nums[j] < nums[k]
|
||||
k = j # 記錄最小元素的索引
|
||||
end
|
||||
end
|
||||
# 將該最小元素與未排序區間的首個元素交換
|
||||
nums[i], nums[k] = nums[k], nums[i]
|
||||
end
|
||||
end
|
||||
```
|
||||
|
||||
=== "Zig"
|
||||
|
||||
Reference in New Issue
Block a user