java实现插入排序算法 附单元测试源码

插入排序算法

public class InsertSortTest {

    /**
     * @param args
     */
    public static void main(String[] args) {
        int[] a={3,5,9,16,29,47,78,89,94};
        int key=47;
        int[] b=insertSort(a,key);
        for(int i=0;i<b.length;i++){
            System.out.print(b[i]+"  ");
        }
    }

    public static int[] insertSort(int[] unsorted,int key){
        int len=unsorted.length;
        int[] sorted=new int[len+1];
        for(int i=0;i<len;i++){
            //when key exists in edge of array
            if(key<unsorted[0]){
                sorted[0]=key;
                System.arraycopy(unsorted, 0, sorted, 1, len);
            }
            if(key>unsorted[len-1]){
                sorted[sorted.length-1]=key;
                System.arraycopy(unsorted, 0, sorted, 0, len);
            }
            //when key exists in mid of array
            if(key>unsorted[i]){
                sorted[i]=unsorted[i];
            }else{
                sorted[i]=key;
                System.arraycopy(unsorted, i, sorted, i+1, len-i);
                break;
            }
        }
        return sorted;
    }
}

单元测试源码：（使用junit4）

public class InsertSortUnitTest {

    @Test
    public void testLT() {
        int[] a={3,5,9,16,29,47,78,89,94};
        int key=-5;
        int[] result={-5,3,5,9,16,29,47,78,89,94};
        int[] b=InsertSortTest.insertSort(a,key);
        for(int i=0;i<result.length;i++){
            assertEquals(result[i],b[i]);
        }
    }

    @Test
    public void testGT() {
        int[] a={3,5,9,16,29,47,78,89,94};
        int key=205;
        int[] result={3,5,9,16,29,47,78,89,94,205};
        int[] b=InsertSortTest.insertSort(a,key);
        for(int i=0;i<result.length;i++){
            assertEquals(result[i],b[i]);
        }
    }

    @Test
    public void testMid() {
        int[] a={3,5,9,16,29,47,78,89,94};
        int key=50;
        int[] result={3,5,9,16,29,47,50,78,89,94};
        int[] b=InsertSortTest.insertSort(a,key);
        for(int i=0;i<result.length;i++){
            assertEquals(result[i],b[i]);
        }
    }

    @Test
    public void testEqual(){
        int[] a={3,5,9,16,29,47,78,89,94};
        int key=47;
        int[] result={3,5,9,16,29,47,47,78,89,94};
        int[] b=InsertSortTest.insertSort(a,key);
        for(int i=0;i<result.length;i++){
            assertEquals(result[i],b[i]);
        }
    }
}

程序进一步优化：

public class InsertSortTest {

    /**
     * @param args
     */
    public static void main(String[] args) {
        Comparable[] a={3f,5f,9f,16f,29f,47f,78f,89f,94f};
        Comparable key=47.78f;
        Comparable[] b=insertSort(a,key);
        for(int i=0;i<b.length;i++){
            System.out.print(b[i]+"  ");
        }
    }

    public static Comparable[] insertSort(Comparable[] unsorted,Comparable key){
        int len=unsorted.length;
        Comparable[] sorted=new Comparable[len+1];
        for(int i=0;i<len;i++){
            //when key exists in edge of array
            if(key.compareTo(unsorted[0])<0){
                sorted[0]=key;
                System.arraycopy(unsorted, 0, sorted, 1, len);
            }
            if(key.compareTo(unsorted[len-1])>0){
                sorted[sorted.length-1]=key;
                System.arraycopy(unsorted, 0, sorted, 0, len);
            }
            //when key exists in mid of array
            if(key.compareTo(unsorted[i])>0){
                sorted[i]=unsorted[i];
            }else{
                sorted[i]=key;
                System.arraycopy(unsorted, i, sorted, i+1, len-i);
                break;
            }
        }
        return sorted;
    }
}

单元测试的就略过了吧。