CombSort.java

package com.sorts;

import com.types.Sort;

/**
 * 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)
 *
 */
class CombSort<T> implements Sort<T> {

    // To find gap between elements
    private int nextGap(int gap) {
        // Shrink gap by Shrink factor
        gap = (gap * 10) / 13;
        return (gap < 1) ? 1 : gap;
    }

    /**
     * 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]
                    swapped = SortUtils.swap(arr, i, i + gap);
                }
            }
        }
        return arr;
    }
}