`luc058.c`¶

Problem Statement

Implement the Insertion Sort algorithm shown in Figure 13.3 on a set of 25 numbers.

Metadata¶

Property	Detail
Author	Amit Dutta amitdutta4255@gmail.com
Date	08 Feb 2026
License	MIT License (See the LICENSE file for details)
Difficulty	Beginner (index: 3 / 10)

Concepts¶

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This concept detection system is still in beta and may occasionally show incorrect or incomplete results.

Array
Pointers
Iteration
Sorting (possible)
Recursion

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Source Code¶

#include <stdio.h>
#include <math.h>
#include <stdlib.h>

void insertion_sort(int *, int);

int main()
{
    int arr[25], i;

    printf("Enter 25 integers for Insertion Sort:\n");
    for (i = 0; i < 25; i++)
    {
        scanf("%d", &arr[i]);
    }

    insertion_sort(arr, 25);

    printf("\nSorted Array:\n");
    for (i = 0; i < 25; i++)
    {
        printf("%d ", arr[i]);
    }
    printf("\n");

    return 0;
}

void insertion_sort(int *arr, int n)
{
    int i, j, key;
    for (i = 1; i < n; i++)
    {
        key = arr[i];
        j = i - 1;

        /* Move elements of arr[0..i-1], that are greater than key,
           to one position ahead of their current position */
        while (j >= 0 && arr[j] > key)
        {
            arr[j + 1] = arr[j];
            j = j - 1;
        }
        arr[j + 1] = key;
    }
}

Explanation¶

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    - Only use the given code. Do NOT assume anything not present.

    - Do NOT add extra examples.

    - Keep explanation clear and short.

    - If something is unclear, say "Not clear from code".

    - Follow the exact format below. Do NOT change headings.

    FORMAT:

    [START]

    ## What it does

    (Explain the overall purpose in 1-2 sentences)

    ## Step-by-step

    (Explain how the code works in steps, simple language)

    ## Key Concepts

    (List concepts like loop, condition, function, etc.)

    ## Notes

    (Mention any limitations, errors, or assumptions)

    [END]

    CODE (luc058.c):

    #include <stdio.h>
    #include <math.h>
    #include <stdlib.h>

    void insertion_sort(int *, int);

    int main()
    {
        int arr[25], i;

        printf("Enter 25 integers for Insertion Sort:\n");
        for (i = 0; i < 25; i++)
        {
            scanf("%d", &arr[i]);
        }

        insertion_sort(arr, 25);

        printf("\nSorted Array:\n");
        for (i = 0; i < 25; i++)
        {
            printf("%d ", arr[i]);
        }
        printf("\n");

        return 0;
    }

    void insertion_sort(int *arr, int n)
    {
        int i, j, key;
        for (i = 1; i < n; i++)
        {
            key = arr[i];
            j = i - 1;

            /* Move elements of arr[0..i-1], that are greater than key,
               to one position ahead of their current position */
            while (j >= 0 && arr[j] > key)
            {
                arr[j + 1] = arr[j];
                j = j - 1;
            }
            arr[j + 1] = key;
        }
    }

luc058.c¶