diff --git a/sorting/heap_sort.c b/sorting/heap_sort.c
index d4c2a563..b5084cc1 100644
--- a/sorting/heap_sort.c
+++ b/sorting/heap_sort.c
@@ -1,3 +1,8 @@
+/**
+ * max_heapify takes O(logn).
+ * build_maxheap takes O(n).
+ * heapsort takes O(nlogn) since it requires above mentioned functions.
+ */
 #include <stdio.h>
 
 void max_heapify(int *a, int i, int n);