MaxHeap.java

package dsa;

public class MaxHeap {
    public static void heapify(int [] array){
        for (int i = array.length /2 - 1; i >= 0 ; i--) {
            heapify(array, i);
        }
    }

    private static void heapify(int [] array, int index){
        var largerIndex = index;

        var leftIndex = (index * 2) + 1;
        if(leftIndex < array.length && array[leftIndex] > array[largerIndex])
            largerIndex = leftIndex;

        var rightIndex = (index * 2) + 2;
        if(rightIndex < array.length && array[rightIndex] > array[largerIndex])
            largerIndex = rightIndex;

        if(index == largerIndex) return;

        swap(array, index, largerIndex);
        heapify(array, largerIndex);
    }

    private static void swap(int [] array, int first, int second) {
        var temp = array[first];
        array[first] = array[second];
        array[second] = temp;
    }

    public static int getKthLargest(int [] array, int k){
        if (k < 1 || k > array.length) 
            throw new IllegalArgumentException();

        var heap = new Heaps();
        for (int i : array) {
            heap.insert(i);
        }
        for (int i = 0; i < k -1 ; i++) {
            heap.remove();
        }
        return heap.max();
    }
}