Some cleanup of qsort and vec

impls/qsort.cpp

@@ -33,13 +33,12 @@ void quicksort(int *arr, int arr_size)
   print_arr(arr, arr_size);
   printf("\n");
 #endif
-  // Optimisation: for small arr_size, a different sort like the
+  // TODO Optimisation: for small arr_size, a different sort like the bubble
-  // bubble sort may be better, instead of initialising new stack
+  // sort may be better, instead of initialising new stack frames.
-  // frames.
   if (arr_size < 2)
     return;
-  // Optimisation: Use some heuristics to figure out a better pivot
+  // TODO Optimisation: Use some heuristics to figure out a better pivot than
-  // than some constant choice of element.
+  // some constant choice of element.
   int pivot       = 0;
   int pivot_value = arr[0];
   for (int i = 1; i < arr_size; ++i)
@@ -57,13 +56,12 @@ void quicksort(int *arr, int arr_size)
   print_arr(arr, arr_size);
   printf("\n");
 #endif
-  // Optimisation: Use a stack to do this instead of recursion.
+  // TODO Optimisation: Use a stack to do this instead of recursion.
   //
-  // This algorithm is similar to a pre order traversal/dfs, in this
+  // This algorithm is similar to a pre order traversal/dfs, in this case on an
-  // case on an array where left and right partition are children
+  // array where left and right partition are children nodes to the original
-  // nodes to the original array node.  Also with recursion there's a
+  // array node.  Also with recursion there's a real risk for very large
-  // real risk for very large ARR_SIZE of running out of space in the
+  // ARR_SIZE of running out of space in the call stack.
-  // call stack.
   if (pivot != 0)
     quicksort(arr, pivot);
   if (pivot < arr_size - 1)

impls/vec.c

@@ -16,7 +16,7 @@
    @brief A vector, consisting of a header and some payload (data).
    @details The idea is that the user must never actually interact with this
    structure directly, only the data involved.  Any vector related functions
-   deal with
+   will take the pointer to the data and look behind it to get the header.
  */
 typedef struct
 {