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@@ -136,19 +136,19 @@ $$
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```python title="radix_sort.py"
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def digit(num: int, exp: int) -> int:
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""" 获取元素 num 的第 k 位,其中 exp = 10^(k-1) """
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"""获取元素 num 的第 k 位,其中 exp = 10^(k-1)"""
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# 传入 exp 而非 k 可以避免在此重复执行昂贵的次方计算
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return (num // exp) % 10
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def counting_sort_digit(nums: list[int], exp: int) -> None:
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""" 计数排序(根据 nums 第 k 位排序) """
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"""计数排序(根据 nums 第 k 位排序)"""
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# 十进制的位范围为 0~9 ,因此需要长度为 10 的桶
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counter = [0] * 10
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n = len(nums)
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# 统计 0~9 各数字的出现次数
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for i in range(n):
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d = digit(nums[i], exp) # 获取 nums[i] 第 k 位,记为 d
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counter[d] += 1 # 统计数字 d 的出现次数
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counter[d] += 1 # 统计数字 d 的出现次数
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# 求前缀和,将“出现个数”转换为“数组索引”
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for i in range(1, 10):
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counter[i] += counter[i - 1]
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@@ -157,14 +157,14 @@ $$
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for i in range(n - 1, -1, -1):
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d = digit(nums[i], exp)
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j = counter[d] - 1 # 获取 d 在数组中的索引 j
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res[j] = nums[i] # 将当前元素填入索引 j
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counter[d] -= 1 # 将 d 的数量减 1
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res[j] = nums[i] # 将当前元素填入索引 j
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counter[d] -= 1 # 将 d 的数量减 1
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# 使用结果覆盖原数组 nums
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for i in range(n):
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nums[i] = res[i]
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def radix_sort(nums: list[int]) -> None:
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""" 基数排序 """
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"""基数排序"""
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# 获取数组的最大元素,用于判断最大位数
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m = max(nums)
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# 按照从低位到高位的顺序遍历
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