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krahets
2024-05-04 19:57:03 +08:00
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docs/chapter_sorting/quick_sort.md
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@@ -353,7 +353,24 @@ comments: true
=== "Ruby"
```ruby title="quick_sort.rb"
[class]{QuickSort}-[func]{partition}
### 哨兵划分 ###
def partition(nums, left, right)
# 以 nums[left] 为基准数
i, j = left, right
while i < j
while i < j && nums[j] >= nums[left]
j -= 1 # 从右向左找首个小于基准数的元素
end
while i < j && nums[i] <= nums[left]
i += 1 # 从左向右找首个大于基准数的元素
end
# 元素交换
nums[i], nums[j] = nums[j], nums[i]
end
# 将基准数交换至两子数组的分界线
nums[i], nums[left] = nums[left], nums[i]
i # 返回基准数的索引
end
```
=== "Zig"
@@ -594,7 +611,18 @@ comments: true
=== "Ruby"
```ruby title="quick_sort.rb"
[class]{QuickSort}-[func]{quick_sort}
### 快速排序类 ###
def quick_sort(nums, left, right)
# 子数组长度不为 1 时递归
if left < right
# 哨兵划分
pivot = partition(nums, left, right)
# 递归左子数组、右子数组
quick_sort(nums, left, pivot - 1)
quick_sort(nums, pivot + 1, right)
end
nums
end
```
=== "Zig"
@@ -1067,9 +1095,38 @@ comments: true
=== "Ruby"
```ruby title="quick_sort.rb"
[class]{QuickSortMedian}-[func]{median_three}
### 选取三个候选元素的中位数 ###
def median_three(nums, left, mid, right)
# 选取三个候选元素的中位数
_l, _m, _r = nums[left], nums[mid], nums[right]
# m 在 l 和 r 之间
return mid if (_l <= _m && _m <= _r) || (_r <= _m && _m <= _l)
# l 在 m 和 r 之间
return left if (_m <= _l && _l <= _r) || (_r <= _l && _l <= _m)
return right
end
[class]{QuickSortMedian}-[func]{partition}
### 哨兵划分（三数取中值）###
def partition(nums, left, right)
### 以 nums[left] 为基准数
med = median_three(nums, left, (left + right) / 2, right)
# 将中位数交换至数组最左断
nums[left], nums[med] = nums[med], nums[left]
i, j = left, right
while i < j
while i < j && nums[j] >= nums[left]
j -= 1 # 从右向左找首个小于基准数的元素
end
while i < j && nums[i] <= nums[left]
i += 1 # 从左向右找首个大于基准数的元素
end
# 元素交换
nums[i], nums[j] = nums[j], nums[i]
end
# 将基准数交换至两子数组的分界线
nums[i], nums[left] = nums[left], nums[i]
i # 返回基准数的索引
end
```
=== "Zig"
@@ -1377,7 +1434,22 @@ comments: true
=== "Ruby"
```ruby title="quick_sort.rb"
[class]{QuickSortTailCall}-[func]{quick_sort}
### 快速排序（尾递归优化）###
def quick_sort(nums, left, right)
# 子数组长度不为 1 时递归
while left < right
# 哨兵划分
pivot = partition(nums, left, right)
# 对两个子数组中较短的那个执行快速排序
if pivot - left < right - pivot
quick_sort(nums, left, pivot - 1)
left = pivot + 1 # 剩余未排序区间为 [pivot + 1, right]
else
quick_sort(nums, pivot + 1, right)
right = pivot - 1 # 剩余未排序区间为 [left, pivot - 1]
end
end
end
```
=== "Zig"