Add time complexity info for sort algorithms

- add time complexity info for all sort algorithm (bubble, heap, insertion and selection)

Author: jciberlin

Inc/sort/bubble_sort.h

@@ -38,7 +38,9 @@
 #include "typedefs.h"
 
 /**
- * @brief Sort elements using bubble sort algorithm.
+ * @brief Sort elements using bubble sort algorithm. It compares the adjacent elements and swaps them
+ * if they are in the wrong order. It is done repeatedly until all elements are sorted.
+ * Time complexity: O(N^2)
  *
  * @param[in/out] *buffer Pointer to the buffer that contains elements that will be sorted.
  * @param[in] number_of_elements Number of elements in the buffer.

Inc/sort/heap_sort.h

@@ -38,7 +38,10 @@
 #include "typedefs.h"
 
 /**
- * @brief Sort elements using heap sort algorithm.
+ * @brief Sort elements using heap sort algorithm. It uses heapify to convert array into max heap.
+ * It deletes the root node of the max heap (one by one) and replaces it with the last node. After that,
+ * heapify is done again. Whole process is repeated while heap size is greater than 1.
+ * Time complexity: O(N log N)
  *
  * @param[in/out] *buffer Pointer to the buffer that contains elements that will be sorted.
  * @param[in] number_of_elements Number of elements in the buffer.

Inc/sort/insertion_sort.h

@@ -40,9 +40,11 @@
 #define MAX_ELEMENT_SIZE (64)
 
 /**
- * @brief Sort elements using insertion sort algorithm. Insertion sort algorithm is a simple
- * sorting algorithm that has O(N^2) time complexity. It is efficient on smaller lists, and
- * much less efficient on large lists.
+ * @brief Sort elements using insertion sort algorithm. Divide given list into sorted and unsorted part
+ * (first element is considered sorted). Iterate through each element in the unsorted part. Pick one
+ * element at a time, and insert it into correct position in the sorted part. It is efficient on smaller
+ * lists, and much less efficient on large lists.
+ * Time complexity: O(N^2)
  *
  * NOTE: implemented that the max element size is 64 B. If element size is larger, then
  * MAX_ELEMENT_SIZE macro must be updated.

Inc/sort/selection_sort.h

@@ -38,13 +38,13 @@
 #include "typedefs.h"
 
 /**
- * @brief Sort elements using selection sort algorithm. Selection sort algorithm is an in-place
- * comparison sorting algorithm that has O(N^2) time complexity. It divides the input array into
+ * @brief Sort elements using selection sort algorithm. It divides the input array into
  * two parts, sorted sub-array of items which is built up from left to right and unsorted items
  * that occupies the rest of the array. The sorted sub-array is empty and the unsorted sub-array
  * is the entire input array. The algorithm proceeds by finding the smallest element in the
  * unsorted sub-array, swapping it with the leftmost unsorted element (putting it in sorted order),
  * and moving the sub-array boundaries one element to the right.
+ * Time complexity: O(N^2)
  *
  * @param[in/out] *buffer Pointer to the buffer that contains elements that will be sorted.
  * @param[in] number_of_elements Number of elements in the buffer.