diff --git a/sorting/heap_sort.c b/sorting/heap_sort.c
index d4c2a5636d..7e2e19f874 100644
--- a/sorting/heap_sort.c
+++ b/sorting/heap_sort.c
@@ -4,6 +4,13 @@ void max_heapify(int *a, int i, int n);
 void heapsort(int *a, int n);
 void build_maxheap(int *a, int n);
 
+/**
+ * max_heapify takes O(logn)
+ * @param a pointer to array a containing heap elements
+ * @param i element at which max_heapify needs to be performed
+ * @param n where n is number of elemnts in array a
+ * @returns void
+ */
 void max_heapify(int *a, int i, int n)
 {
     int j, temp;
@@ -39,6 +46,12 @@ void heapsort(int *a, int n)
     }
 }
 
+/**
+ * build_maxheap takes O(n)
+ * @param a pointer to array a containing heap elements
+ * @param n where n is number of elemnts in array a
+ * @returns void
+ */
 void build_maxheap(int *a, int n)
 {
     int i;