2.1.3 Insertion Sort

以後再補說明

package idv.carl.sorting.insertionsort;

/**
 * @author Carl Lu
 */
public class InsertionSort {

    private static void swap(int[] input, int i, int j) {
        int tmp = input[i];
        input[i] = input[j];
        input[j] = tmp;
    }

    public static int[] sortDesc(int[] input) {
        for (int i = 0; i < input.length - 1; i++) {
            for (int j = i + 1; j > 0; j--) {
                if (input[j - 1] < input[j]) {
                    swap(input, j - 1, j);
                }
            }
        }
        return input;
    }

    public static int[] sortAsc(int[] input) {
        for (int i = 0; i < input.length - 1; i++) {
            for (int j = i + 1; j > 0; j--) {
                if (input[j - 1] > input[j]) {
                    swap(input, j - 1, j);
                }
            }
        }
        return input;
    }
}

原始碼點我

Unit test:

package idv.carl.sorting.insertionsort;

import static org.junit.Assert.assertArrayEquals;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;

/**
 * @author Carl Lu
 */
public class InsertionSortTest {

    private static int[] input;
    private static int[] expectedDesc = new int[] {45, 34, 26, 13, 12, 9, 7, 3, 1, -1};
    private static int[] expectedAsc = new int[] {-1, 1, 3, 7, 9, 12, 13, 26, 34, 45};

    @Before
    public void init() {
        input = new int[] {12, 45, 1, 3, -1, 34, 13, 7, 9, 26};
    }

    @After
    public void destroy() {
        input = null;
    }

    @Test
    public void testSortDesc() {
        assertArrayEquals(expectedDesc, InsertionSort.sortDesc(input));
    }

    @Test
    public void testSortAsc() {
        assertArrayEquals(expectedAsc, InsertionSort.sortAsc(input));
    }
}

原始碼點我