In shellSort, we make the array h-sorted for a large value of h. We keep reducing the value of h until it becomes 1. An array is said to be h-sorted if all sublists of every h’th element is sorted.
Java
// Java implementation of ShellSort class ShellSort {
/* An utility function to print array of size n*/
static void printArray( int arr[])
{
int n = arr.length;
for ( int i = 0 ; i < n; ++i)
System.out.print(arr[i] + " " );
System.out.println();
}
/* function to sort arr using shellSort */
int sort( int arr[])
{
int n = arr.length;
// Start with a big gap, then reduce the gap
for ( int gap = n / 2 ; gap > 0 ; gap /= 2 ) {
// Do a gapped insertion sort for this gap size.
// The first gap elements a[0..gap-1] are already
// in gapped order keep adding one more element
// until the entire array is gap sorted
for ( int i = gap; i < n; i += 1 ) {
// add a[i] to the elements that have been gap
// sorted save a[i] in temp and make a hole at
// position i
int temp = arr[i];
// shift earlier gap-sorted elements up until
// the correct location for a[i] is found
int j;
for (j = i; j >= gap && arr[j - gap] > temp; j -= gap)
arr[j] = arr[j - gap];
// put temp (the original a[i]) in its correct
// location
arr[j] = temp;
}
}
return 0 ;
}
// Driver method
public static void main(String args[])
{
int arr[] = { 12 , 34 , 54 , 2 , 3 };
System.out.println( "Array before sorting" );
printArray(arr);
ShellSort ob = new ShellSort();
ob.sort(arr);
System.out.println( "Array after sorting" );
printArray(arr);
}
} /*This code is contributed by Rajat Mishra */ |
Output:
Array before sorting 12 34 54 2 3 Array after sorting 2 3 12 34 54
Time Complexity: O(n2)
Auxiliary Space: O(1)
Please refer complete article on ShellSort for more details!