Python: Find the kth largest element in an unsorted array using Heap queue algorithm

Last update on April 01 2025 13:22:09 (UTC/GMT +8 hours)

7. Kth Largest Element

Write a Python program to find the k^th (1 <= k <= array's length) largest element in an unsorted array using the heap queue algorithm.

Sample Solution:

Python Code:

import heapq

class Solution(object):
    def find_Kth_Largest(self, nums, k):
        """
        :type nums: List[int]
        :type of k: int
        :return value type: int
        """
        h = []
        for e in nums:
            heapq.heappush(h, (-e, e))
        for i in range(k):
            w, e = heapq.heappop(h)
            if i == k - 1:
                return e

arr_nums = [12, 14, 9, 50, 61, 41]
s = Solution()
result = s.find_Kth_Largest(arr_nums, 3)
print("Third largest element:",result)
result = s.find_Kth_Largest(arr_nums, 2)
print("\nSecond largest element:",result)
result = s.find_Kth_Largest(arr_nums, 5)
print("\nFifth largest element:",result)

Sample Output:

Third largest element: 41

Second largest element: 50

Fifth largest element: 12

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to find the kth largest element in an unsorted list using heapq.nlargest and return the kth element.
• Write a Python function that maintains a min-heap of size k to determine the kth largest number from a stream of integers.
• Write a Python script to extract the kth largest element from an array using a heap-based approach and validate the result with sorting.
• Write a Python program to compute the kth largest element in a list by using heapq to maintain a running heap of the top k elements.

Python Code Editor:

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