setting up automatic testing harness
sort: testing harness
sorts: added harness to selection sort
sorts: added harness to insertion sort
sorts: added harness to merge sort and deleted sentinelles
more elegant merge sort, with only one mem alloc
integer sorts: pigeonhole sort
sorts: s/pigeonhole/bucket and scan array the first time to find out the maximal value
sorts test harness: add more details when there's a test failure
sorts: radix with std::list
substring: naive implementation
parenthesis problem: given n, generate all valid parenthesis empty statements of size 2n
problems: sum of binary numbers
problems: list all ways to sum with integers to a given integer N