703. Kth Largest Element in a Stream

Easy (Dễ) Python 🔗 Xem trên LeetCode

📋 Đề Bài

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) Appends the integer val to the stream and 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.

🧠 Thuật Toán & Kỹ Thuật

Heap / Priority Queue (Heap / Hàng đợi ưu tiên)
⏱️ Thời gian O(n)
💾 Không gian O(n)

💻 Lời Giải

Python 0703-kth-largest-element-in-a-stream.py 
class KthLargest:

    def __init__(self, k: int, nums: List[int]):
        self.k = k
        self.heap = []
        
        for num in nums:
            heappush(self.heap, num)

    def add(self, val: int) -> int:
        heappush(self.heap, val)
        while len(self.heap) > self.k:
            heappop(self.heap)
        return self.heap[0]

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