daily/287easy/kaprekar.{c,pas}: Use more maths for a cleaner (?) solution

2 files changed, 12 insertions, 32 deletions

diff --git a/daily/287easy/kaprekar.c b/daily/287easy/kaprekar.c
index 3121d88..0cf1bf6 100644
--- a/daily/287easy/kaprekar.c
+++ b/daily/287easy/kaprekar.c
@@ -40,19 +40,14 @@ short desc_digits(short n)
 	return a[0] * 1000 + a[1] * 100 + a[2] * 10 + a[3];
 }
 
-short asc_digits(short n)
-{
-	sort_digits(n);
-
-	return a[3] * 1000 + a[2] * 100 + a[1] * 10 + a[0];
-}
-
 unsigned long long kaprekar(short n)
 {
 	char i;
 
-	for (i = 0; n ^ 6174; i++)
-		n = desc_digits(n) - asc_digits(n);
+	for (i = 0; n ^ 6174; i++) {
+		sort_digits(n);
+		n = (a[0] - a[3]) * 999 + (a[1] - a[2]) * 90;
+	}
 
 	return i;
 }
diff --git a/daily/287easy/kaprekar.pas b/daily/287easy/kaprekar.pas
index 7378f2d..f7a7f46 100644
--- a/daily/287easy/kaprekar.pas
+++ b/daily/287easy/kaprekar.pas
@@ -1,5 +1,5 @@
-type
-  aos = array[0 .. 3] of shortint;
+var
+  a: array[0 .. 3] of shortint;
 
 function largest_digit(n: smallint): shortint;
   var
@@ -20,9 +20,8 @@ function largest_digit(n: smallint): shortint;
       exit(m)
   end;
 
-function sorted_digits(n: smallint): aos;
+procedure sort_digits(n: smallint);
   var
-    a: aos;
     i, j: shortint;
 
   begin
@@ -38,31 +37,16 @@ function sorted_digits(n: smallint): aos;
             inc(a[i], a[j]);
             a[j] := a[i] - a[j];
             dec(a[i], a[j])
-          end;
-
-    exit(a)
+          end
   end;
 
 function desc_digits(n: smallint): smallint;
-  var
-    a: aos;
-
   begin
-    a := sorted_digits(n);
+    sort_digits(n);
 
     exit(a[0] * 1000 + a[1] * 100 + a[2] * 10 + a[3])
   end;
 
-function asc_digits(n: smallint): smallint;
-  var
-    a: aos;
-
-  begin
-    a := sorted_digits(n);
-
-    exit(a[3] * 1000 + a[2] * 100 + a[1] * 10 + a[0])
-  end;
-
 function kaprekar(n: smallint): qword;
   var
     i: shortint = 0;
@@ -70,8 +54,9 @@ function kaprekar(n: smallint): qword;
   begin
     while n <> 6174 do
       begin
-        n := desc_digits(n) - asc_digits(n);
-        inc(i)
+        inc(i);
+        sort_digits(n);
+        n := (a[0] - a[3]) * 999 + (a[1] - a[2]) * 90
       end;
 
     exit(i)