C Exercises: Sort numbers using shell sorting method

Last update on March 20 2025 12:39:03 (UTC/GMT +8 hours)

10. Shell Sort Variants

Write a C program that sorts numbers using the shell sorting method.

According to Wikipedia "Shell sort or Shell's method, is an in-place comparison sort. It can be seen as either a generalization of sorting by exchange (bubble sort) or sorting by insertion (insertion sort). The method starts by sorting pairs of elements far apart from each other, then progressively reducing the gap between elements to be compared. Starting with far apart elements can move some out-of-place elements into position faster than a simple nearest neighbor exchange."

Sample Solution:

Sample C Code:

// https://bit.ly/2rcvXK5
// Shell Sort Implementation
// Source: https://bit.ly/2rcvXK5
#include <stdio.h>
// Function to perform shell sort on an array
void shell_sort(int *a, int n) {
    int h, i, j, t;
    // Iterate over different values of h (gap sequence)
    for (h = n; h /= 2;) {
        // Iterate through the array with the current gap h
        for (i = h; i < n; i++) {
            t = a[i];
            // Insertion sort within the subarrays created by the gap
            for (j = i; j >= h && t < a[j - h]; j -= h) {
                a[j] = a[j - h];
            }
            // Place the current element in its correct position
            a[j] = t;
        }
    }
}
// Main function
int main(int ac, char **av) {
    // Input array
    int a[] = {4, 65, 2, -31, 0, 99, 2, 83, 782, 1};
    int n = sizeof a / sizeof a[0];
    int i;
    // Display original array
    printf("Original Array:\n");
    for (i = 0; i < n; i++)
        printf("%d%s", a[i], i == n - 1 ? "\n" : " ");
    // Sort the array using shell sort
    shell_sort(a, n);
    // Display sorted array
    printf("\nSorted Array:\n");
    for (i = 0; i < n; i++)
        printf("%d%s", a[i], i == n - 1 ? "\n" : " ");
    return 0;
}

Sample Output:

Original Array:
4 65 2 -31 0 99 2 83 782 1

Sorted Array:
-31 0 1 2 2 4 65 83 99 782

Flowchart:

For more Practice: Solve these Related Problems:

Write a C program to implement shell sort with a dynamic gap sequence and print each intermediate sorted state.
Write a C program to sort an array of integers using shell sort and then find the kth smallest element.
Write a C program to implement shell sort on an array of floating-point numbers and verify the sorted order.
Write a C program to optimize shell sort using the Sedgewick gap sequence and count comparisons.

C Programming Code Editor:

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