ADVANCED DATA STRUCTURES PROGRAM • LEVEL 12 — ADVANCED SORTING

Sort with Shell Gap Reduction

Learn how to sort with shell gap reduction using a clear C program.

AdvancedAdvanced sortingOrdering

PROBLEM UNDERSTANDING

Input and expected output

Sample input

No input required

Sample output

2 3 12 34 54

COMPLETE C PROGRAM

Complete C implementation

#include <stdio.h>

void print_values(const int values[], int count) { for (int i = 0; i < count; i++) printf("%d%c", values[i], i == count - 1 ? '\n' : ' '); }

int main(void)
{
    int values[] = {12, 34, 54, 2, 3};
    for (int gap = 5 / 2; gap > 0; gap /= 2)
        for (int i = gap; i < 5; i++) {
            int value = values[i], j = i;
            while (j >= gap && values[j - gap] > value) { values[j] = values[j - gap]; j -= gap; }
            values[j] = value;
        }
    print_values(values, 5); return 0;
}

CURRENT STEP

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SELECTED LINE

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EXPECTED OUTPUT FOR THE SAMPLE

2 3 12 34 54

0%Step 0 of 0

PROGRAM EXPLANATION

Algorithm and explanation

Read the required input values.
Insertion-sort distant elements first, then reduce the gap until it becomes one.
Display the computed result.

Insertion-sort distant elements first, then reduce the gap until it becomes one.

EFFICIENCY

Time and space complexity

Time complexity

Depends on gap sequence

Auxiliary space

O(1)

DEBUGGING CHECKLIST

Common mistakes

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Use the correct format specifier for every variable.

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Initialize variables before using their values.

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Check braces, semicolons and input order carefully.

Try it yourself

Practice: Run the program with the sample input, predict its output, and then test one boundary case of your own.