Sorting Algorithms in C

Sorting Algorithms in C

Sorting Algorithms are the rules defined by the programmer that allows rearranging the provided list into a specified order. The expected output is nothing but the Sorted List. These Data Structures are utilized for sorting the given list into expected outcomes. Sorting is essential in every sector. Handling data becomes easier once you sort them. Hence, sorting becomes vital from the programming aspect as well. Many beginners prefer the C programming language while still in the learning phase. It is a system programming language; hence, it will encourage you to understand programming from scratch.

Learning Sorting Algorithms in C will be the better option as you can code it from scratch with ease and understand it better. Two primary conditions must be satisfied by the output of all the Sorting Algorithms. The first condition is that the output must be in monotonic order, and the second condition is that the output must be the permutation of the input. Whenever you come across the Sorting Algorithm in C, the algorithms that immediately come into the picture are Bubble Sort, Selection Sort, Insertion Sort, Quick Sort, and Merge Sort. 

Bubble Sort is considered to be the most straightforward Sorting Algorithm. It allows you to sort the given array in the intended order by repeatedly shifting the adjacent elements to put them in the proper order. The name bubble comes from the idea of the air bubbles found in the water that float to the surface. In the same way, the numbers in the array of the Bubble Sort keep shifting to find their proper place for the numbers to be in the intended order. Hence, the name Bubble Sort. 

The algorithm of Bubble Sort, a Sorting Algorithm in C is as below:

BubbleSort(array, size)

for i = 0 to n

for j=0 to n-i-1

If array[j] > array[j+1]

Swap array[j] and array[j+1]  

The pseudocode for Bubble Sort in C is as below:

void bubbleSort(int array[]) { 

int size = array.length; 

for (int i = 0; i < size; i++) 

for (int j = 0; j < size - i - 1; j++) 

if (array[j] > array[j + 1]) { 

int temp = array[j]; 

array[j] = array[j + 1]; 

array[j + 1] = temp; 

} 

}

If you are trying to sort out the array in ascending order, You will start comparing the elements from the first index. You compare the first index with its adjacent element, which becomes your second element. If the first element is found greater than the second element, the elements get swapped. Now you compare the second element with the third element. If these elements are not in the correct order, they get switched. This is the first iteration. This iteration repeats, and through these iterations, the large elements are placed at the end of the array in the intended order, and the elements in the array get sorted in ascending order.

Quick Sort is a Sorting Algorithm and is based on the divide and conquer approach, which is being utilized vastly. You have an unsorted array that needs to be sorted with the help of Quick Sort. You have to carry out with the Quick Sort in a way where you have to select a pivot from the array. It must be placed in such a manner where the elements left to the pivot must be less than the value of the pivot element, and on the right of the pivot, the element’s value must be greater than the pivot element’s value. Thus, the array is divided into two subarrays. The same approach is applied for sorting the created subarrays. Hence, the subarrays will be sorted and merged to get the final sorted array. 

void quickSort(int[] a, int p, int r)

{

if(p<r)

{

int q = partition(a,p,r);

quickSort(a,p,q-1);

quickSort(a,q+1,r);

}

}

int partition_function(int arr[], int l, int h)

{

int pivot = arr[h];

int index = (l-1);

for(int j = 1; j<=h-1; j++)

{

if(arr[j] < p)

{

I++;

swap_elements(&arr[i], &arr[j]);

}

}

swap_elements(&arr[i+1], &arr[h]);

return(i+1);

}

Merge Sort is also a Sorting Algorithm that depends on the divide and conquer algorithm. This algorithm is used to divide the problem into subproblems, and the solutions for these subproblems are found. The solutions for these subproblems are then combined to get the solution for the major problem. In the same way, if an array A is provided, we tend to divide it into halves where we have two subarrays A[p...q] and A[q+1...r]. We combine these two sorted subarrays to get a solution for array A[p...r]. You will understand the Merge sort better by looking at the implementation below:

void mergeSort(int arr[], int start, int right) 

{ 

if (start < right) 

{ 

int mid = (start + right) / 2; 

mergeSort(arr, start, mid); 

mergeSort(arr, mid + 1, right); 

merge(arr, start, mid, right); 

} 

}

void merge(int arr[], int start, int mid, int end) 

{

 int len1 = mid - start + 1;

 int len2 = end - mid;

int leftArr[len1], rightArr[len2];

for (int i = 0; i < len1; i++)

{leftArr[i] = arr[start + i];}

for (int j = 0; j < len2; j++)

  {rightArr[j] = arr[mid + 1 + j];}

int i, j, k;

 i = 0;

 j = 0;

 k = start;

 while (i < len1 && j < len2) 

{

  if (leftArr[i] <= rightArr[j]) {

  arr[k] = leftArr[i];

  i++;

 } else {

 arr[k] = rightArr[j];

 j++;

 }

 k++;

 }

}

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