Leetcode: Kth Largest Element in a Stream

Kth Largest Element in a Stream

Similar Problems:

Design a class to find the kth largest element in a stream. Note that it is the kth largest element in the sorted order, not the kth distinct element.

Your KthLargest class will have a constructor which accepts an integer k and an integer array nums, which contains initial elements from the stream. For each call to the method KthLargest.add, return the element representing the kth largest element in the stream.


int k = 3;
int[] arr = [4,5,8,2];
KthLargest kthLargest = new KthLargest(3, arr);
kthLargest.add(3);   // returns 4
kthLargest.add(5);   // returns 5
kthLargest.add(10);  // returns 5
kthLargest.add(9);   // returns 8
kthLargest.add(4);   // returns 8


  • You may assume that nums’ length >= k-1 and k >= 1.

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.

  • Solution: heap
## Blog link: https://code.dennyzhang.com/kth-largest-element-in-a-stream
## Basic Ideas: min heap
## Complexity: Time O(log(k)), Space O(k)
import heapq
class KthLargest:

    def __init__(self, k, nums):
        :type k: int
        :type nums: List[int]
        self.q = []
        self.k = k
        for num in nums:
            heapq.heappush(self.q, num)
            if len(self.q) > k: heapq.heappop(self.q)

    def add(self, val):
        :type val: int
        :rtype: int
        heapq.heappush(self.q, val)
        if len(self.q) > self.k: heapq.heappop(self.q)
        return self.q[0]

# Your KthLargest object will be instantiated and called as such:
# obj = KthLargest(k, nums)
# param_1 = obj.add(val)

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