Truncatable primes: Difference between revisions

Content deleted Content added

Inline

@@ Line 272: / Line 272: @@
 }
-bool isLeftTruncatablePrime(int n) {
+bool isTruncatablePrime(bool left)(int n) {
   string s = to!string(n);
   if (indexOf(s, '0') != -1)
     return false;
   foreach (i; 0 .. s.length)
-    if (!isPrime(to!int(s[i .. $])))
+    static if (left) {
+      if (!isPrime(to!int(s[i .. $])))
-      return false;
-  return true;
+        return false;
+    } else {
-}
+      if (!isPrime(to!int(s[0 .. i+1])))
+        return false;
-bool isRightTruncatablePrime(int n) {
+    }
-  string s = to!string(n);
-  if (indexOf(s, '0') != -1)
-    return false;
-  foreach (i; 0 .. s.length)
-    if (!isPrime(to!int(s[0 .. i+1])))
-      return false;
   return true;
 }
@@ Line 295: / Line 290: @@
   enum int n = 1_000_000;
   foreach_reverse (i; 2 .. n)
-    if (isLeftTruncatablePrime(i)) {
+    if (isTruncatablePrime!true(i)) {
       writeln("Largest left-truncatable prime in 2 .. ", n, ": ", i);
       break;
     }
   foreach_reverse (i; 2 .. n)
-    if (isRightTruncatablePrime(i)) {
+    if (isTruncatablePrime!false(i)) {
       writeln("Largest right-truncatable prime in 2 .. ", n, ": ", i);
       break;