Start chapter 2, switch to ng-backed build.

ods/notes/chapter1.txt

@@ -166,6 +166,12 @@ Run times come in three flavours:
       might be a doubly-linked list with the iteration direction determined by
       distance from the centre, though this comes at the cost of additional
       complexity. The same improvements would apply to remove.
+
+      On a randomised benchmark (random operation, random value, random index),
+      the array-backed list still outperforms a from-scratch linked list and
+      an STL vector wrapper. The linked list performs the worst, with wildly
+      varying run times.
+
    2. For the sorted list, a basic improvement for find would be to pick the
       middle of the list and do an equality check, basically bisecting to
       find where the value *would* be.

ods/notes/chapter2.txt

@@ -0,0 +1,15 @@
+# Chapter 2 (Array-based lists)
+
+These data structures have common advantages and limitations:
+
+* constant-time access
+
+* resizing the array adds potentially non-trivial complexity, both in time and
+  storage, as a new array generally must be created and the old array copied
+  over.
+
+* arrays aren't dynamic, which means inserting or deleting in the middle of an
+  array requires shifting all the following elements.
+
+With some careful management, the additional *amortised* complexity added by
+resizing isn't too bad.

ods/src/build.yaml

@@ -1,6 +1,6 @@
 compilers:
-  cxx: clang++-5.0
-  ld: clang++-5.0
+  cxx: clang++
+  ld: clang++
 
 targets:
   cc: