(1) Direct insertion sort
① Principle:
The entire interval is divided into:
1. Ordered interval
2. Unordered interval
Each time the first element of the unordered interval is selected, select the appropriate position to insert in the ordered interval
②Code implementation:
public class insertSort {
public static void main(String[] args) {
int[] array={
1,5,78,6,4,8,45,12,0,88};
System.out.println(Arrays.toString(array));
inSort(array);
System.out.println(Arrays.toString(array));
}
// 直接插入排序，稳定的排序，时间复杂度：O(n^2),空间复杂度：O(1)
//越有序，越快
public static void inSort(int[] array){
for(int i=1;i<array.length;i++){
int tmp=array[i];
for(int j=i-1;j>=0;j--){
if(array[j]>tmp){
array[j+1]=array[j];
}else{
break;
}
array[j]=tmp;
}
}
}
}
Run screenshot:
③Performance analysis
Stability: stable
Insertion sort, the closer the initial data is to order, the higher the time efficiency.
(2) Hill sort
① Principle:
Hill sorting method is also called reduced increment method . The basic idea of Hill sorting method is: first select an integer, divide all the records in the file to be sorted into groups, group all records with a distance of 1 into the same group, and sort the records in each group. Then, take and repeat the above grouping and sorting work. When it reaches =1, all records are sorted in the unified group.
1. Hill sorting is an optimization of direct insertion sorting.
2. When gap> 1, all are pre-sorted, the purpose is to make the array closer to order. When gap == 1, the array is already close to order, so it will be very fast. In this way, as a whole, an optimized effect can be achieved. After we realize it, we can compare the performance test.
②Code implementation:
public class insertSort {
public static void main(String[] args) {
int[] array={
1,5,78,6,88,4,8,45,12,0};
System.out.println(Arrays.toString(array));
shellSort(array);
System.out.println(Arrays.toString(array));
}
//希尔排序（分组的思想）,缩小增量排序
//时间复杂度：O(1.5)~O(n^2),空间复杂度：O(1) 稳定性：不稳定
public static void shellSort(int[] array){
int[] arr={
5,3,1};
for(int i=0;i<arr.length;i++){
shell(array,arr[i]);
}
}
public static void shell(int[] array,int gap){
for(int i=gap;i<array.length;i++){
int tmp=array[i];
for(int j=i-gap;j>=0;j=j-gap){
if(array[j]>tmp){
array[j+gap]=array[j];
}else{
break;
}
array[j]=tmp;
}
}
}
}
Run screenshot:
③Performance analysis
Stability: unstable