Heap Sort

public class HeapSort {
    public static void sort(int arr[]) {
        int n = arr.length;
        for (int i = (n / 2) - 1; i >= 0; i--) {
            heapify(arr, n, i);
        }
        System.out.println("After max  heapify");
        print(arr);

        for (int i = n - 1; i >= 0; i--) {
            swap(arr, i, 0);
            heapify(arr, i, 0);
        }
        System.out.println();
        System.out.println("After sort");
        print(arr);
    }

    public static void print(int[] arr) {
        for (int num : arr) {
            System.out.print(num + " ");

        }
    }

    public static void heapify(int[] arr, int n, int index) {
        int left = index * 2 + 1;
        int right = index * 2 + 2;
        int largestIndex = index;
        if (left < n && arr[largestIndex] < arr[left]) {
            largestIndex = left;
        }
        if (right < n && arr[largestIndex] < arr[right]) {
            largestIndex = right;
        }
        if (largestIndex != index) {
            swap(arr, index, largestIndex);
            heapify(arr, n, largestIndex);
        }
    }

    public static void swap(int[] arr, int i, int j) {
        int temp = arr[i];
        arr[i] = arr[j];
        arr[j] = temp;
    }

    public static void main(String[] args) {
        int arr[] = { 12, 11, 13, 5, 6, 7 };
        sort(arr);
    }

}