ocaml: phase 5.1 catalan.ml baseline (Catalan number C(5) = 42)

DP recurrence:

  C(0) = 1
  C(n) = sum_{j=0}^{n-1} C(j) * C(n-1-j)

  let catalan n =
    let dp = Array.make (n + 1) 0 in
    dp.(0) <- 1;
    for i = 1 to n do
      for j = 0 to i - 1 do
        dp.(i) <- dp.(i) + dp.(j) * dp.(i - 1 - j)
      done
    done;
    dp.(n)

C(5) = 42 — also the count of distinct binary trees with 5 internal
nodes, balanced paren strings of length 10, monotonic lattice paths,
etc.

106 baseline programs total.

lib/ocaml/baseline/expected.json

@@ -18,6 +18,7 @@
   "bsearch.ml": 7,
   "caesar.ml": 215,
   "calc.ml": 13,
+  "catalan.ml": 42,
   "closures.ml": 315,
   "coin_change.ml": 6,
   "count_change.ml": 406,