From 6497917352c73371730e50f063acd61cf4268076 Mon Sep 17 00:00:00 2001 From: Neha <129765919+neha3423@users.noreply.github.com> Date: Thu, 26 Oct 2023 14:24:30 +0530 Subject: [PATCH] Added Kth largest element algorithm (#10687) * neha3423 * neha3423 * neha3423 * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * neha3423 * neha3423 * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * neha323 * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * neha3423 * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * neha3423 * neha3423 * neha3423 * neha3423 * Added test case for tuple * Update kth_largest_element.py --------- Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com> Co-authored-by: Christian Clauss --- data_structures/arrays/kth_largest_element.py | 117 ++++++++++++++++++ 1 file changed, 117 insertions(+) create mode 100644 data_structures/arrays/kth_largest_element.py diff --git a/data_structures/arrays/kth_largest_element.py b/data_structures/arrays/kth_largest_element.py new file mode 100644 index 000000000..f25cc68e9 --- /dev/null +++ b/data_structures/arrays/kth_largest_element.py @@ -0,0 +1,117 @@ +""" +Given an array of integers and an integer k, find the kth largest element in the array. + +https://stackoverflow.com/questions/251781 +""" + + +def partition(arr: list[int], low: int, high: int) -> int: + """ + Partitions list based on the pivot element. + + This function rearranges the elements in the input list 'elements' such that + all elements greater than or equal to the chosen pivot are on the right side + of the pivot, and all elements smaller than the pivot are on the left side. + + Args: + arr: The list to be partitioned + low: The lower index of the list + high: The higher index of the list + + Returns: + int: The index of pivot element after partitioning + + Examples: + >>> partition([3, 1, 4, 5, 9, 2, 6, 5, 3, 5], 0, 9) + 4 + >>> partition([7, 1, 4, 5, 9, 2, 6, 5, 8], 0, 8) + 1 + >>> partition(['apple', 'cherry', 'date', 'banana'], 0, 3) + 2 + >>> partition([3.1, 1.2, 5.6, 4.7], 0, 3) + 1 + """ + pivot = arr[high] + i = low - 1 + for j in range(low, high): + if arr[j] >= pivot: + i += 1 + arr[i], arr[j] = arr[j], arr[i] + arr[i + 1], arr[high] = arr[high], arr[i + 1] + return i + 1 + + +def kth_largest_element(arr: list[int], position: int) -> int: + """ + Finds the kth largest element in a list. + Should deliver similar results to: + ```python + def kth_largest_element(arr, position): + return sorted(arr)[-position] + ``` + + Args: + nums: The list of numbers. + k: The position of the desired kth largest element. + + Returns: + int: The kth largest element. + + Examples: + >>> kth_largest_element([3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5], 3) + 5 + >>> kth_largest_element([2, 5, 6, 1, 9, 3, 8, 4, 7, 3, 5], 1) + 9 + >>> kth_largest_element([2, 5, 6, 1, 9, 3, 8, 4, 7, 3, 5], -2) + Traceback (most recent call last): + ... + ValueError: Invalid value of 'position' + >>> kth_largest_element([9, 1, 3, 6, 7, 9, 8, 4, 2, 4, 9], 110) + Traceback (most recent call last): + ... + ValueError: Invalid value of 'position' + >>> kth_largest_element([1, 2, 4, 3, 5, 9, 7, 6, 5, 9, 3], 0) + Traceback (most recent call last): + ... + ValueError: Invalid value of 'position' + >>> kth_largest_element(['apple', 'cherry', 'date', 'banana'], 2) + 'cherry' + >>> kth_largest_element([3.1, 1.2, 5.6, 4.7,7.9,5,0], 2) + 5.6 + >>> kth_largest_element([-2, -5, -4, -1], 1) + -1 + >>> kth_largest_element([], 1) + -1 + >>> kth_largest_element([3.1, 1.2, 5.6, 4.7, 7.9, 5, 0], 1.5) + Traceback (most recent call last): + ... + ValueError: The position should be an integer + >>> kth_largest_element((4, 6, 1, 2), 4) + Traceback (most recent call last): + ... + TypeError: 'tuple' object does not support item assignment + """ + if not arr: + return -1 + if not isinstance(position, int): + raise ValueError("The position should be an integer") + if not 1 <= position <= len(arr): + raise ValueError("Invalid value of 'position'") + low, high = 0, len(arr) - 1 + while low <= high: + if low > len(arr) - 1 or high < 0: + return -1 + pivot_index = partition(arr, low, high) + if pivot_index == position - 1: + return arr[pivot_index] + elif pivot_index > position - 1: + high = pivot_index - 1 + else: + low = pivot_index + 1 + return -1 + + +if __name__ == "__main__": + import doctest + + doctest.testmod()