Solver for "Calculator - The Game"

A fun little game that deserves a solver.

Call the solution function with:

solution [starting num] [goal num] [number of moves] [list of buttons] [portal]

Operations have the following signature:

type operation =
    Add of int
  | Sub of int
  | Mul of int
  | Div of int
  | Square
  | Cube
  | Del
  | MulNeg
  | Append of int
  | Replace of string * string
  | Shift of int
  | Reverse
  | Sum
  | Inv10
  | Mirror
  | MetaInc of int
  | StoreSave
  | StoreUse

Portals are either None if not present or Some (portal [portal entry] [portal exit]) where entry < exit and we start counting from the right (and from 0).

Examples

Level 134

> solution 0 34 3 [Append 2; Append 3; MetaInc 1] None;;
[+]1 ➔ 3 ➔ 4

Level 155

> solution 9 3001 9 [Replace("39", "93"); StoreSave; StoreUse; Div 3; Replace("31", "00")] None;;
store (s) ➔ /3 ➔ store (u) ➔ store (s) ➔ store (u) ➔ 39=>93 ➔ 39=>93 ➔ /3 ➔ 31=>00

(store (s) is long press and store (u) is single press)

Level 168

> solution 26 99 6 [Sum; Inv10; Append 2] None;;
2 ➔ sum ➔ Inv10 ➔ 2 ➔ sum ➔ Inv10

Level 185

# solution 525 150 5 [Add 1; Append 6; Append 7; Div 2] (Some (portal 0 3));;
7 ➔ 6 ➔ /2 ➔ 6 ➔ +1

Level 188

# solution 25 822 6 [Mirror; Append 5; StoreUse; StoreSave; Del] (Some (portal 1 3));;
5 ➔ mirror ➔ store (s) ➔ store (u)

(solution in 4 moves instead of the 6 expected)

Level 199

# solution 3002 3507 6 [Append 7; Replace("3","5"); Inv10; Shift 1] (Some (portal 0 4));;
7 ➔ 3=>5 ➔ 7 ➔ shift> ➔ Inv10 ➔ 7

Tests

Need alcotest, then ocamlbuild -pkg alcotest -pkg str calc_solver_tests.native && ./calc_solver_tests.native