[LeetCode] Problem 703 - Kth Largest Element in a Stream

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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.

Example

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

Note

You may assume that nums’ length ≥ k-1 and k ≥ 1.

Code

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private PriorityQueue<Integer> minHeap = new PriorityQueue<>();
private int size;

public KthLargest(int k, int[] nums) {
    size = k;

    for (int num : nums)
        add(num);
}

public int add(int val) {
    minHeap.offer(val);

    if (minHeap.size() > size)
        minHeap.poll();

    return minHeap.peek();
}