Sorting algorithms are essential tools in computer science, enabling the arrangement of data for easier retrieval and manipulation. Among these algorithms, Radix Sort stands out as a unique and efficient approach for sorting integers. In this article, we will delve into the mechanics of the Radix Sort algorithm in c, provide a step-by-step guide, and present its implementation in the C programming language.

Introducing Radix Sort Algorithm

Radix Sort is a non-comparative integer sorting algorithm that takes advantage of the positional notation of numbers. It sorts the input integers digit by digit, from the least significant digit (LSD) to the most significant digit (MSD) or vice versa. This characteristic makes Radix Sort particularly useful for sorting large sets of integers.

How Radix Sort Works

The working of the Radix Sort algorithm can be broken down into these steps:

Initial Array: Begin with an unsorted array of integers.
Sorting by Digits: Start by sorting the integers based on their least significant digit (LSD). Group the integers into buckets based on each digit’s value (0 to 9). Place the integers with the same digit value in the same bucket.
Collecting Buckets: Collect the integers from the buckets in the order they were placed (from 0 to 9).
Sorting Process: Repeat the sorting process for each successive digit, moving from the least significant digit to the most significant digit (or vice versa). After each pass, collect the integers from the buckets again.
Sorted Array: After sorting through all the digits, the array will be fully sorted.

Implementing Radix Sort in C

Here’s an example implementation of Radix Sort in C:

#include <stdio.h>

int getMax(int arr[], int n) {
    int max = arr[0];
    for (int i = 1; i < n; i++) {
        if (arr[i] > max) {
            max = arr[i];
        }
    }
    return max;
}

void countingSort(int arr[], int n, int exp) {
    int output[n];
    int count[10] = {0};

    for (int i = 0; i < n; i++) {
        count[(arr[i] / exp) % 10]++;
    }

    for (int i = 1; i < 10; i++) {
        count[i] += count[i - 1];
    }

    for (int i = n - 1; i >= 0; i--) {
        output[count[(arr[i] / exp) % 10] - 1] = arr[i];
        count[(arr[i] / exp) % 10]--;
    }

    for (int i = 0; i < n; i++) {
        arr[i] = output[i];
    }
}

void radixSort(int arr[], int n) {
    int max = getMax(arr, n);

    for (int exp = 1; max / exp > 0; exp *= 10) {
        countingSort(arr, n, exp);
    }
}

int main() {
    int arr[] = {170, 45, 75, 90, 802, 24, 2, 66};
    int n = sizeof(arr) / sizeof(arr[0]);

    radixSort(arr, n);

    printf("Sorted array: ");
    for (int i = 0; i < n; i++) {
        printf("%d ", arr[i]);
    }
    return 0;
}

Advantages and Limitations

Radix Sort offers several advantages and limitations:

Advantages:

Radix Sort maintains stability, which means that the relative order of equal elements remains the same after sorting.
It is efficient for sorting a large number of integers.

Limitations:

Radix Sort is specifically designed for integers and may require modification for other data types.
It may not be suitable for smaller datasets due to its overhead in maintaining buckets and counts.

Frequently Asked Questions (FAQs) About Radix Sort

1. What is Radix Sort?

Radix Sort is a non-comparative integer sorting algorithm that works by sorting numbers digit by digit, from the least significant digit (LSD) to the most significant digit (MSD) or vice versa. It takes advantage of the positional notation of numbers to achieve efficient sorting without the need for direct element comparisons.

2. What is Radix Sort in Data Structure?

In the realm of data structures, Radix Sort is a sorting algorithm that utilizes the structure of numbers themselves to achieve sorting. It breaks down the sorting process into multiple passes, sorting the numbers based on their individual digits. This algorithm’s efficiency lies in its exploitation of positional notation, making it particularly useful for sorting large sets of integers.

3. What is the time complexity of Radix Sort?

The time complexity of Radix Sort depends on the number of digits (digits in the largest number) and the number of elements to be sorted. If there are n elements with d digits each, the time complexity of Radix Sort is O(d * (n + k)), where k is the range of values for each digit (typically 10 for decimal digits). However, if the number of digits (d) is constant or very small relative to the number of elements (n), the time complexity can be simplified to O(n * k), making Radix Sort an efficient sorting option for large datasets.

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Radix Sort Algorithm in C – Data Structures and Algorithm