From 95ebd2d6acfa744c5e93287cc6385f4f1359376e Mon Sep 17 00:00:00 2001
From: Jedidiah Barber <contact@jedbarber.id.au>
Date: Sun, 30 Oct 2022 03:42:11 +1300
Subject: wallgen and wallsolve working, visualwall partially done, license
 added

---
 src/wall.ml | 337 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 337 insertions(+)
 create mode 100644 src/wall.ml

(limited to 'src/wall.ml')

diff --git a/src/wall.ml b/src/wall.ml
new file mode 100644
index 0000000..94043dc
--- /dev/null
+++ b/src/wall.ml
@@ -0,0 +1,337 @@
+
+
+(* Programmed by Jedidiah Barber *)
+(* Licensed under the Sunset License v1.0 *)
+
+
+module type Algebra =
+  sig
+    type t
+    val zero : t
+    val one : t
+    val add : t -> t -> t
+    val sub : t -> t -> t
+    val mul : t -> t -> t
+    val div : t -> t -> t
+    val to_string : t -> string
+  end
+
+
+
+module type S =
+  sig
+    type element
+    type wall
+    val create : dimx:int -> dimy:int -> init:element array -> wall
+    val x_length : wall -> int
+    val y_length : wall -> int
+    val has_value : wall -> x:int -> y:int -> bool
+    val get : wall -> x:int -> y:int -> element
+    val get_opt : wall -> x:int -> y:int -> element option
+    val last_nonzero_row : wall -> int
+    val to_string : wall -> string
+    val print : wall -> unit
+    val output : Stdlib.out_channel -> wall -> unit
+    val pp_print : Stdlib.Format.formatter -> wall -> unit
+  end
+
+
+
+let (let*?) = Option.bind
+
+
+
+module Make (A : Algebra) =
+  struct
+
+    type element = A.t
+    type wall = element option array array
+
+    let x_length wall =
+      Array.length wall
+
+    let y_length wall =
+      Array.length wall.(0)
+
+    let has_value wall ~x ~y =
+      if x >= 0 && x < x_length wall &&
+         y >= 0 && y < y_length wall
+      then match wall.(x).(y) with
+          None -> false
+        | Some _ -> true
+      else false
+
+    let get_opt wall ~x ~y =
+      if x >= 0 && x < x_length wall &&
+         y >= 0 && y < y_length wall
+      then wall.(x).(y)
+      else None
+
+
+
+    let next_nonzero_up wall ~x ~y =
+      let rec walker y1 =
+        let*? v = get_opt wall ~x ~y:y1 in
+        if v <> A.zero then Some y1 else walker (y1-1)
+      in walker y
+
+    let next_nonzero_left wall ~x ~y =
+      let rec walker x1 =
+        let*? v = get_opt wall ~x:x1 ~y in
+        if v <> A.zero then Some x1 else walker (x1-1)
+      in walker x
+
+    let next_nonzero_right wall ~x ~y =
+      let rec walker x1 =
+        let*? v = get_opt wall ~x:x1 ~y in
+        if v <> A.zero then Some x1 else walker (x1+1)
+      in walker x
+
+
+
+    let next_valid_left wall ~x ~y =
+      let rec walker x1 =
+        if x1 < 0
+        then None
+        else if Option.is_some (get_opt wall ~x:x1 ~y)
+          then Some x1
+          else walker (x1-1) in
+      walker x
+
+
+
+    let safe_div a b =
+      if b = A.zero then None else Some (A.div a b)
+
+    let multi_mul items =
+      let f a b = A.mul a b in
+      List.fold_left f A.one items
+
+    let square a =
+      A.mul a a
+
+    let rec power ~base ~num ~denom ~times =
+      if times <= 0
+      then Some base
+      else let*? new_base = safe_div (A.mul base num) denom in
+        power ~base:new_base ~num ~denom ~times:(times-1)
+
+
+
+    (* red x red + green x green = blue squared *)
+    (* target to calculate is red on the bottom of the cross *)
+    (* current cell x two up + one diag up left x one diag up right = one up squared *)
+    let cross_rule wall ~x ~y =
+      let*? green_left = get_opt wall ~x:(x-1) ~y:(y-1) in
+      let*? green_right = get_opt wall ~x:(x+1) ~y:(y-1) in
+      let*? blue = get_opt wall ~x ~y:(y-1) in
+      let*? red_top = get_opt wall ~x ~y:(y-2) in
+      safe_div (A.sub (square blue) (A.mul green_left green_right)) red_top
+
+
+
+    (* outer yellow x inner yellow squared + outer blue x inner blue squared *)
+    (* equals outer grey x inner grey squared + outer red x inner red squared *)
+    (* inner yellow is up, outer yellow is down *)
+    (* inner blue is down, outer blue is up *)
+    (* inner grey is left, outer grey is right *)
+    (* inner red is right, outer red is left *)
+    (* target to calculate is outer yellow *)
+    let long_cross_rule wall ~x ~y =
+      let*? outer_red = get_opt wall ~x:(x-2) ~y:(y-2) in
+      let*? inner_red = get_opt wall ~x:(x+1) ~y:(y-2) in
+      let*? red_product = Some (A.mul outer_red (square inner_red)) in
+      let*? outer_grey = get_opt wall ~x:(x+2) ~y:(y-2) in
+      let*? inner_grey = get_opt wall ~x:(x-1) ~y:(y-2) in
+      let*? grey_product = Some (A.mul outer_grey (square inner_grey)) in
+      let*? grey_red_sum = Some (A.add grey_product red_product) in
+      let*? outer_blue = if y - 4 = -1 then Some A.zero else get_opt wall ~x ~y:(y-4) in
+      let*? inner_blue = get_opt wall ~x ~y:(y-1) in
+      let*? blue_product = Some (A.mul outer_blue (square inner_blue)) in
+      let*? greyred_blue_diff = Some (A.sub grey_red_sum blue_product) in
+      let*? inner_yellow = get_opt wall ~x ~y:(y-3) in
+      safe_div greyred_blue_diff (square inner_yellow)
+
+
+
+    (* All blocks of zeros in the wall come in squares. *)
+    let zero_window wall ~x ~y =
+      let*? top = next_nonzero_up wall ~x ~y:(y-1) in
+      let*? left = next_nonzero_left wall ~x ~y:(top+1) in
+      let*? right = next_nonzero_right wall ~x ~y:(top+1) in
+      if y - 1 > top && right - left > 0 && right - left + 1 > y - 1 - top
+      then Some A.zero
+      else None
+
+
+
+    (* denote ratio of top sequence from left to right as a/b *)
+    (* denote ratio of bottom sequence from right to left as c/d *)
+    (* denote ratio of left sequence from top to bottom as e/f *)
+    (* denote ratio of right sequence from bottom to top as g/h *)
+    (* denote rhs as s *)
+    (* s is 1 when even sized window and -1 when odd sized window *)
+    (* goal is to calculate c/d *)
+    (* then *)
+    (* ((a/b)(c/d))/((e/f)(g/h)) = s *)
+    (* (a/b)(c/d) = s(e/f)(g/h) *)
+    (* (a/b)(c/d) = (seg)/(fh) *)
+    (* c/d = ((seg)/(fh))(b/a) *)
+    (* c/d = (begs)/(afh) *)
+    (* and since that ratio is going from right to left, invert to go left to right *)
+    (* thus to transform bottom left corner number into next number... *)
+    (* multiply by afh then divide by begs *)
+    let horseshoe_rule wall ~x ~y =
+      let*? top = next_nonzero_up wall ~x ~y:(y-1) in
+      let*? left = next_nonzero_left wall ~x ~y:(top+1) in
+      let*? right = next_nonzero_right wall ~x ~y:(top+1) in
+      let*? _ = if y - top <> right - left || right - left <= 2 then None else Some 1 in
+      let*? a = get_opt wall ~x:(left+1) ~y:top in
+      let*? b = get_opt wall ~x:left     ~y:top in
+      let*? e = get_opt wall ~x:left     ~y:(top+1) in
+      let*? f = get_opt wall ~x:left     ~y:top in
+      let*? g = get_opt wall ~x:right    ~y:top in
+      let*? h = get_opt wall ~x:right    ~y:(top+1) in
+      let*? s = if (right - left - 1) mod 2 = 0 then Some A.one else Some (A.sub A.zero A.one) in
+      let*? prev = next_valid_left wall ~x ~y in
+      power
+        ~base:(Option.get wall.(prev).(y))
+        ~num:(A.mul (A.mul a f) h)
+        ~denom:(A.mul (A.mul (A.mul b e) g) s)
+        ~times:(x - prev)
+
+
+
+    (* denote ratio of top sequence from left to right as a/b *)
+    (* denote ratio of bottom sequence from right to left as c/d *)
+    (* denote ratio of left sequence from top to bottom as e/f *)
+    (* denote ratio of right sequence from bottom to top as g/h *)
+    (* denote sign of grey/red terms as s *)
+    (* goal is to calculate outer yellow *)
+    (* and also to put off division until the very end to ensure integer intermediate results *)
+    (* then *)
+    (* (e/f)(o_bl/i_bl) + s(a/b)(o_gr/i_gr) = (g/h)(o_ye/i_ye) + s(c/d)(o_re/i_re) *)
+    (* (e/f)(o_bl/i_bl) + s(a/b)(o_gr/i_gr) - s(c/d)(o_re/i_re) = (g/h)(o_ye/i_ye) *)
+    (* i_ye((e/f)(o_bl/i_bl) + s(a/b)(o_gr/i_gr) - s(c/d)(o_re/i_re)) = (g/h)o_ye *)
+    (* o_ye = i_ye(h/g)((e/f)(o_bl/i_bl) + s(a/b)(o_gr/i_gr) - s(c/d)(o_re/i_re)) *)
+    (* o_ye = i_ye(h/g)((e*o_bl)/(f*i_bl) + s(a*o_gr)/(b*i_gr) - s(c*o_re)/(d*i_re)) *)
+    (* o_ye = h*i_ye*(e*o_bl*b*i_gr*d*i_re + s*a*o_gr*f*i_bl*d*i_re - s*c*o_re*f*i_bl*b*i_gr) / *)
+    (*        (g*f*i_bl*b*i_gr*d*i_re) *)
+    let broken_cross_rule wall ~x ~y =
+      let*? top = next_nonzero_up wall ~x ~y:(y-2) in
+      let*? left = next_nonzero_left wall ~x ~y:(top+1) in
+      let*? right = next_nonzero_right wall ~x ~y:(top+1) in
+      let*? bottom = Some (y - 1) in
+      let*? _ = if bottom - top <> right - left || right - left <= 2 then None else Some 1 in
+      let*? a = get_opt wall ~x:(left+1) ~y:top in
+      let*? b = get_opt wall ~x:left     ~y:top in
+      let*? c = get_opt wall ~x:left     ~y:bottom in
+      let*? d = get_opt wall ~x:(left+1) ~y:bottom in
+      let*? e = get_opt wall ~x:left     ~y:(top+1) in
+      let*? f = get_opt wall ~x:left     ~y:top in
+      let*? g = get_opt wall ~x:right    ~y:top in
+      let*? h = get_opt wall ~x:right    ~y:(top+1) in
+      let*? s = if (right - x) mod 2 = 0 then Some A.one else Some (A.sub A.zero A.one) in
+      let*? inner_yellow = get_opt wall ~x                ~y:bottom in
+      let*? inner_blue   = get_opt wall ~x:(right-x+left) ~y:top in
+      let*? inner_red    = get_opt wall ~x:right          ~y:(bottom-right-x) in
+      let*? inner_grey   = get_opt wall ~x:left           ~y:(right-x+top) in
+      let*? outer_blue   = get_opt wall ~x:(right-x+left) ~y:(top-1) in
+      let*? outer_red    = get_opt wall ~x:(right+1)      ~y:(bottom-right-x) in
+      let*? outer_grey   = get_opt wall ~x:(left-1)       ~y:(right-x+top) in
+      let*? term_1 = Some (multi_mul [   e; outer_blue; b; inner_grey; d; inner_red]) in
+      let*? term_2 = Some (multi_mul [s; a; outer_grey; f; inner_blue; d; inner_red]) in
+      let*? term_3 = Some (multi_mul [s; c; outer_red;  f; inner_blue; b; inner_grey]) in
+      let*? term_sum = Some (A.sub (A.add term_1 term_2) term_3) in
+      let*? numerator = Some (multi_mul [h; inner_yellow; term_sum]) in
+      let*? denominator = Some (multi_mul [g; f; inner_blue; b; inner_grey; d; inner_red]) in
+      safe_div numerator denominator
+
+
+
+    let rec attempt_order wall ~x ~y funcs =
+      if funcs = []
+      then None
+      else let r = (List.hd funcs) wall ~x ~y in
+        if Option.is_some r
+        then r
+        else attempt_order wall ~x ~y (List.tl funcs)
+
+    let create ~dimx ~dimy ~init =
+      let result = Array.make_matrix dimx dimy None in
+      for i = 0 to dimx - 1 do
+        result.(i).(0) <- Some A.one
+      done;
+      for i = 0 to min (dimx - 1) ((Array.length init) - 1) do
+        result.(i).(1) <- Some init.(i)
+      done;
+      try
+        for j = 2 to dimy - 1 do
+          let do_exit = ref true in
+          for i = 0 to dimx - 1 do
+            let v = attempt_order result ~x:i ~y:j
+              [cross_rule; long_cross_rule; zero_window; horseshoe_rule; broken_cross_rule] in
+            result.(i).(j) <- v;
+            if Option.is_some v && Option.get v <> A.zero
+            then do_exit := false
+          done;
+          if !do_exit then raise Exit
+        done;
+        result
+      with Exit ->
+        result
+
+
+
+    let get wall ~x ~y =
+      if x >= 0 && x < x_length wall &&
+         y >= 0 && y < y_length wall
+      then match wall.(x).(y) with
+          None -> raise Not_found
+        | Some v -> v
+      else raise Not_found
+
+    let last_nonzero_row wall =
+      let rec checker x y =
+        if wall.(x).(y) <> Some A.zero && wall.(x).(y) <> None
+        then (if y + 1 = y_length wall then y else checker 0 (y + 1))
+        else (if x + 1 = x_length wall then y - 1 else checker (x + 1) y)
+      in checker 0 0
+
+
+
+    let row_string wall ~y =
+      let result = ref "" in
+      for i = 0 to (x_length wall) - 2 do
+        let v = wall.(i).(y) in
+        if Option.is_some v
+        then result := !result ^ (A.to_string (Option.get v)) ^ ","
+        else result := !result ^ ","
+      done;
+      let v = wall.(x_length wall - 1).(y) in
+      if Option.is_some v
+      then result := !result ^ (A.to_string (Option.get v));
+      !result
+
+    let to_string wall =
+      let result = ref "" in
+      for j = 0 to (y_length wall) - 1 do
+        result := !result ^ (row_string wall ~y:j) ^ (String.make 1 (char_of_int 10))
+      done;
+      !result
+
+    let print wall =
+      print_string (to_string wall)
+
+    let output channel wall =
+      output_string channel (to_string wall)
+
+    let pp_print format wall =
+      for j = 0 to (y_length wall) - 1 do
+        Format.pp_print_string format (row_string wall ~y:j);
+        Format.pp_print_break format 8 0
+      done
+
+  end
+
+
-- 
cgit