Find the kth largest element in an unsorted array.

1-kth-largest-in-array.js

export function findKthLargest(arr, k) {
  // we are going to have min heap of size k
  // it means the top of the heap is going to be the minimum element
  // of all k elements in the heap
  // which is exactly the kth largest element that we need
  const heap = new MinHeap();

  for (let i = 0; i < k; ++i) {
    // initialize the heap with the first k elements from the array
    heap.offer(arr[i]);
  }

  for (let i = k; i < arr.length; ++i) {
    // iterate the rest of the array
    if (arr[i] > heap.peek()) {
      // if array element is larger than the top of the heap,
      // it means top of the heap is not part of the k largest elements,
      // so we remove it, and push the current element to the heap
      heap.poll();
      heap.offer(arr[i]);
    }
  }

  // top of the min heap is the kth largest element
  return heap.peek();
}

2-README.md