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.
CPP
// C++ implementation of Shell Sort #include <iostream> /* function to sort arr using shellSort */ void shellSort( int arr[], int n) { // 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 arr[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 arr[i] to the elements that have been gap sorted // save arr[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 arr[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 arr[i]) in its correct location arr[j] = temp; } } } void printArray( int arr[], int n) { for ( int i = 0; i < n; i++) std::cout << arr[i] << " " ; std::cout << "\n" ; } int main() { int arr[] = { 12, 34, 54, 2, 3 }; int n = sizeof (arr) / sizeof (arr[0]); std::cout << "Array before sorting: \n" ; printArray(arr, n); shellSort(arr, n); std::cout << "Array after sorting: \n" ; printArray(arr, n); } |
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!
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