Data commit

Task/Zig-zag-matrix/ATS/zig-zag-matrix.ats

@@ -0,0 +1,62 @@
+(* ****** ****** *)
+//
+#include
+"share/atspre_define.hats" // defines some names
+#include
+"share/atspre_staload.hats" // for targeting C
+#include
+"share/HATS/atspre_staload_libats_ML.hats" // for ...
+//
+(* ****** ****** *)
+//
+extern
+fun
+Zig_zag_matrix(n: int): void
+//
+(* ****** ****** *)
+
+fun max(a: int, b: int): int =
+  if a > b then a else b
+
+fun movex(n: int, x: int, y: int): int =
+  if y < n-1 then max(0, x-1) else x+1
+
+fun movey(n: int, x: int, y: int): int =
+  if y < n-1 then y+1 else y
+
+fun zigzag(n: int, i: int, row: int, x: int, y: int): void =
+  if i = n*n then ()
+  else
+    let
+      val () = (if x = row then begin print i; print ','; end else ())
+      //val () = (begin print x; print ' '; print y; print ' '; print i; print ' '; end)
+      val nextX: int = if ((x+y) % 2) = 0 then movex(n, x, y) else movey(n, y, x)
+      val nextY: int = if ((x+y) % 2) = 0 then movey(n, x, y) else movex(n, y, x)
+    in
+      zigzag(n, i+1, row, nextX, nextY)
+    end
+
+implement
+Zig_zag_matrix(n) =
+  let
+    fun loop(row: int): void =
+      if row = n then () else
+        let
+          val () = zigzag(n, 0, row, 0, 0)
+          val () = println!(" ")
+        in
+          loop(row + 1)
+        end
+  in
+    loop(0)
+  end
+
+(* ****** ****** *)
+
+implement
+main0() = () where
+{
+  val () = Zig_zag_matrix(5)
+} (* end of [main0] *)
+
+(* ****** ****** *)