LeetCode 703. Kth Largest Element in a Stream

Description

https://leetcode.com/problems/kth-largest-element-in-a-stream/

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.

Implement KthLargest class:

  • KthLargest(int k, int[] nums) Initializes the object with the integer k and the stream of integers nums.
  • int add(int val) Returns the element representing the kth largest element in the stream.

Example 1:

Input
["KthLargest", "add", "add", "add", "add", "add"]
[[3, [4, 5, 8, 2]], [3], [5], [10], [9], [4]]
Output

[null, 4, 5, 5, 8, 8]

Explanation KthLargest kthLargest = new KthLargest(3, [4, 5, 8, 2]); kthLargest.add(3); // return 4 kthLargest.add(5); // return 5 kthLargest.add(10); // return 5 kthLargest.add(9); // return 8 kthLargest.add(4); // return 8

Constraints:

  • 1 <= k <= 104
  • 0 <= nums.length <= 104
  • -104 <= nums[i] <= 104
  • -104 <= val <= 104
  • At most 104 calls will be made to add.
  • It is guaranteed that there will be at least k elements in the array when you search for the kth element.

Explanation

A simple solution is to sort the list whenever adding a new value and then find the kth largest value.

Python Solution

class KthLargest:

    def __init__(self, k: int, nums: List[int]):
        
        self.nums = nums
        self.k = k
        
    def add(self, val: int) -> int:
        self.nums.append(val)
        self.nums = sorted(self.nums)
                
        return self.nums[len(self.nums) - self.k]

# Your KthLargest object will be instantiated and called as such:
# obj = KthLargest(k, nums)
# param_1 = obj.add(val)
  • Time Complexity: O(NlogN).
  • Space Complexity: O(N).

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