recursion.ml

let rec max_product_recursive grid rows cols i j =
  if i >= rows then 0
  else if j >= cols then max_product_recursive grid rows cols (i + 1) 0
  else
    let max_in_position =
      let max_val = ref 0 in
      (* Горизонтально *)
      if j + 3 < cols then
        max_val := max !max_val (grid.(i).(j) * grid.(i).(j+1) * grid.(i).(j+2) * grid.(i).(j+3));
      (* Вертикально *)
      if i + 3 < rows then
        max_val := max !max_val (grid.(i).(j) * grid.(i+1).(j) * grid.(i+2).(j) * grid.(i+3).(j));
      (* Диагональ вправо вниз *)
      if i + 3 < rows && j + 3 < cols then
        max_val := max !max_val (grid.(i).(j) * grid.(i+1).(j+1) * grid.(i+2).(j+2) * grid.(i+3).(j+3));
      (* Диагональ вправо вверх *)
      if i - 3 >= 0 && j + 3 < cols then
        max_val := max !max_val (grid.(i).(j) * grid.(i-1).(j+1) * grid.(i-2).(j+2) * grid.(i-3).(j+3));
      !max_val
    in
    max max_in_position (max_product_recursive grid rows cols i (j + 1))

let max_product grid =
  let rows = Array.length grid in
  let cols = Array.length grid.(0) in
  max_product_recursive grid rows cols 0 0;;


(* Пример использования *)
let grid = [|
  [|08; 02; 22; 97; 38; 15; 00; 40; 00; 75; 04; 05; 07; 78; 52; 12; 50; 77; 91; 08|];
  [|49; 49; 99; 40; 17; 81; 18; 57; 60; 87; 17; 40; 98; 43; 69; 48; 04; 56; 62; 00|];
  [|81; 49; 31; 73; 55; 79; 14; 29; 93; 71; 40; 67; 53; 88; 30; 03; 49; 13; 36; 65|];
  [|52; 70; 95; 23; 04; 60; 11; 42; 69; 24; 68; 56; 01; 32; 56; 71; 37; 02; 36; 91|];
  [|22; 31; 16; 71; 51; 67; 63; 89; 41; 92; 36; 54; 22; 40; 40; 28; 66; 33; 13; 80|];
  [|24; 47; 32; 60; 99; 03; 45; 02; 44; 75; 33; 53; 78; 36; 84; 20; 35; 17; 12; 50|];
  [|32; 98; 81; 28; 64; 23; 67; 10; 26; 38; 40; 67; 59; 54; 70; 66; 18; 38; 64; 70|];
  [|67; 26; 20; 68; 02; 62; 12; 20; 95; 63; 94; 39; 63; 08; 40; 91; 66; 49; 94; 21|];
  [|24; 55; 58; 05; 66; 73; 99; 26; 97; 17; 78; 78; 96; 83; 14; 88; 34; 89; 63; 72|];
  [|21; 36; 23; 09; 75; 00; 76; 44; 20; 45; 35; 14; 00; 61; 33; 97; 34; 31; 33; 95|];
  [|78; 17; 53; 28; 22; 75; 31; 67; 15; 94; 03; 80; 04; 62; 16; 14; 09; 53; 56; 92|];
  [|16; 39; 05; 42; 96; 35; 31; 47; 55; 58; 88; 24; 00; 17; 54; 24; 36; 29; 85; 57|];
  [|86; 56; 00; 48; 35; 71; 89; 07; 05; 44; 44; 37; 44; 60; 21; 58; 51; 54; 17; 58|];
  [|19; 80; 81; 68; 05; 94; 47; 69; 28; 73; 92; 13; 86; 52; 17; 77; 04; 89; 55; 40|];
  [|04; 52; 08; 83; 97; 35; 99; 16; 07; 97; 57; 32; 16; 26; 26; 79; 33; 27; 98; 66|];
  [|88; 36; 68; 87; 57; 62; 20; 72; 03; 46; 33; 67; 46; 55; 12; 32; 63; 93; 53; 69|];
  [|04; 42; 16; 73; 38; 25; 39; 11; 24; 94; 72; 18; 08; 46; 29; 32; 40; 62; 76; 36|];
  [|20; 69; 36; 41; 72; 30; 23; 88; 34; 62; 99; 69; 82; 67; 59; 85; 74; 04; 36; 16|];
  [|20; 73; 35; 29; 78; 31; 90; 01; 74; 31; 49; 71; 48; 86; 81; 16; 23; 57; 05; 54|];
  [|01; 70; 54; 71; 83; 51; 54; 69; 16; 92; 33; 48; 61; 43; 52; 01; 89; 19; 67; 48|];
|];;
let result = max_product grid;;
print_int result;;