開発メモ

開発用のメモです。

コンボソート

ソース

package jp.mirageworld.algorithm.sort;

import java.util.ArrayList;
import java.util.List;

public class ComboSort {

    public static <T extends Comparable<T>> List<T> sort(List<T> list) {
        List<T> retList = new ArrayList<T>(list);

        boolean next = true;
        int last = retList.size();
        int h = (last * 10) / 13;
        while (next) {
            int s = 0;
            next = false;
            for (int i = 0; i + h < last; i++) {
                T a = retList.get(i + 0);
                T b = retList.get(i + h);
                if (a.compareTo(b) > 0) {
                    retList.set(i + 0, b);
                    retList.set(i + h, a);
                    next = true;
                    s++;
                }
            }
            if (h == 1 && s == 0) {
                break;
            } else if (h == 1) {
                continue;
            } else {
                h = (h * 10) / 13;
            }
        }
        return retList;
    }
}

テストケース

package jp.mirageworld.algorithm.sort;

import static org.junit.Assert.*;

import java.util.Collections;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;

import org.junit.Test;

public class ComboSortTest {

    @Test
    public void testSort() {
        Set<Long> set = new HashSet<>();
        Long target = Math.round(Math.random() * 50);
        while (set.size() < 50) {
            set.add(Math.round(Math.random() * 50 + set.size() * 50));
        }
        List<Long> list = new LinkedList<>(set);
        target = list.get(target.intValue());

        List<Long> retList = ComboSort.sort(list);

        System.out.println(list);
        System.out.println(retList);

        Collections.sort(list);
        assertEquals(list.toString(), retList.toString());
        System.out.println(list);
    }

}
Twitter: @asahina_alice