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118 lines
3.6 KiB
Python
118 lines
3.6 KiB
Python
"""
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Given an array of integers and an integer k, find the kth largest element in the array.
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https://stackoverflow.com/questions/251781
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"""
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def partition(arr: list[int], low: int, high: int) -> int:
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"""
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Partitions list based on the pivot element.
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This function rearranges the elements in the input list 'elements' such that
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all elements greater than or equal to the chosen pivot are on the right side
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of the pivot, and all elements smaller than the pivot are on the left side.
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Args:
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arr: The list to be partitioned
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low: The lower index of the list
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high: The higher index of the list
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Returns:
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int: The index of pivot element after partitioning
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Examples:
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>>> partition([3, 1, 4, 5, 9, 2, 6, 5, 3, 5], 0, 9)
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4
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>>> partition([7, 1, 4, 5, 9, 2, 6, 5, 8], 0, 8)
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1
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>>> partition(['apple', 'cherry', 'date', 'banana'], 0, 3)
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2
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>>> partition([3.1, 1.2, 5.6, 4.7], 0, 3)
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1
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"""
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pivot = arr[high]
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i = low - 1
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for j in range(low, high):
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if arr[j] >= pivot:
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i += 1
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arr[i], arr[j] = arr[j], arr[i]
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arr[i + 1], arr[high] = arr[high], arr[i + 1]
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return i + 1
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def kth_largest_element(arr: list[int], position: int) -> int:
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"""
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Finds the kth largest element in a list.
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Should deliver similar results to:
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```python
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def kth_largest_element(arr, position):
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return sorted(arr)[-position]
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```
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Args:
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nums: The list of numbers.
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k: The position of the desired kth largest element.
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Returns:
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int: The kth largest element.
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Examples:
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>>> kth_largest_element([3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5], 3)
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5
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>>> kth_largest_element([2, 5, 6, 1, 9, 3, 8, 4, 7, 3, 5], 1)
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9
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>>> kth_largest_element([2, 5, 6, 1, 9, 3, 8, 4, 7, 3, 5], -2)
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Traceback (most recent call last):
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...
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ValueError: Invalid value of 'position'
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>>> kth_largest_element([9, 1, 3, 6, 7, 9, 8, 4, 2, 4, 9], 110)
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Traceback (most recent call last):
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...
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ValueError: Invalid value of 'position'
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>>> kth_largest_element([1, 2, 4, 3, 5, 9, 7, 6, 5, 9, 3], 0)
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Traceback (most recent call last):
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...
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ValueError: Invalid value of 'position'
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>>> kth_largest_element(['apple', 'cherry', 'date', 'banana'], 2)
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'cherry'
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>>> kth_largest_element([3.1, 1.2, 5.6, 4.7,7.9,5,0], 2)
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5.6
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>>> kth_largest_element([-2, -5, -4, -1], 1)
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-1
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>>> kth_largest_element([], 1)
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-1
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>>> kth_largest_element([3.1, 1.2, 5.6, 4.7, 7.9, 5, 0], 1.5)
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Traceback (most recent call last):
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...
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ValueError: The position should be an integer
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>>> kth_largest_element((4, 6, 1, 2), 4)
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Traceback (most recent call last):
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...
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TypeError: 'tuple' object does not support item assignment
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"""
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if not arr:
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return -1
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if not isinstance(position, int):
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raise ValueError("The position should be an integer")
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if not 1 <= position <= len(arr):
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raise ValueError("Invalid value of 'position'")
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low, high = 0, len(arr) - 1
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while low <= high:
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if low > len(arr) - 1 or high < 0:
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return -1
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pivot_index = partition(arr, low, high)
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if pivot_index == position - 1:
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return arr[pivot_index]
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elif pivot_index > position - 1:
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high = pivot_index - 1
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else:
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low = pivot_index + 1
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return -1
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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