package cn.iocoder.yudao.framework.common.thealgorithms.sorts;

/**
 * Comb Sort algorithm implementation
 *
 * <p>
 * Best-case performance O(n * log(n)) Worst-case performance O(n ^ 2)
 * Worst-case space complexity O(1)
 *
 * <p>
 * Comb sort improves on bubble sort.
 *
 * @author Sandeep Roy (https://github.com/sandeeproy99)
 * @author Podshivalov Nikita (https://github.com/nikitap492)
 * @see BubbleSort
 * @see SortAlgorithm
 */
class CombSort implements SortAlgorithm {

    // To find gap between elements
    private int nextGap(int gap) {
        // Shrink gap by Shrink factor
        gap = (gap * 10) / 13;
        return Math.max(gap, 1);
    }

    /**
     * Function to sort arr[] using Comb
     *
     * @param arr - an array should be sorted
     * @return sorted array
     */
    @Override
    public <T extends Comparable<T>> T[] sort(T[] arr) {
        int size = arr.length;

        // initialize gap
        int gap = size;

        // Initialize swapped as true to make sure that loop runs
        boolean swapped = true;

        // Keep running while gap is more than 1 and last iteration caused a swap
        while (gap != 1 || swapped) {
            // Find next gap
            gap = nextGap(gap);

            // Initialize swapped as false so that we can check if swap happened or not
            swapped = false;

            // Compare all elements with current gap
            for (int i = 0; i < size - gap; i++) {
                if (SortUtils.less(arr[i + gap], arr[i])) {
                    // Swap arr[i] and arr[i+gap]
                    SortUtils.swap(arr, i, i + gap);
                    swapped = true;
                }
            }
        }
        return arr;
    }

    // Driver method
    public static void main(String[] args) {
        CombSort ob = new CombSort();
        Integer[] arr = {
            8,
            4,
            1,
            56,
            3,
            -44,
            -1,
            0,
            36,
            34,
            8,
            12,
            -66,
            -78,
            23,
            -6,
            28,
            0,
        };
        ob.sort(arr);

        System.out.println("sorted array");
        SortUtils.print(arr);
    }
}
