Truncatable primes: Difference between revisions

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@@ Line 2,320: / Line 2,320: @@
 =={{header|Pike}}==
+<lang Pike>bool is_trunc_prime(int p, string direction)
-<lang Pike>
-array get_primes(int roof)
-{
-    int p = 2;
-    array primes = ({});
-    do {
-	primes += ({ p });
-	p = p->next_prime();
-    } while (p < roof);
-    return primes;
-}
-bool is_prime(int candidate)
-{
-    if( (candidate-1)->next_prime() == candidate )
-	return true;
-    return false;
-}
-bool is_lt_prime(int p)
 {
     while(p) {
-	if( !is_prime(p) )
+	if( !p->probably_prime_p() )
 	    return false;
+	if(direction == "l")
-	p = (int)p->digits()[1..];
+	    p = (int)p->digits()[1..];
-    }
+	else
-    return true;
+	    p = (int)p->digits()[..<1];
-}
-bool is_rt_prime(int p)
-{
-    while(p) {
-	if( !is_prime(p) )
-	    return false;
-	p = (int)p->digits()[..<1];
     }
     return true;
@@ Line 2,361: / Line 2,335: @@
 void main()
 {
-    array primes = get_primes( 10->pow(6) );
     bool ltp_found, rtp_found;
-    foreach( reverse(primes), int prime ) {
+    for(int prime = 10->pow(6); prime--; prime > 0) {
-	if( !ltp_found && is_lt_prime(prime) ) {
+	if( !ltp_found && is_trunc_prime(prime, "l") ) {
 	    ltp_found = true;
 	    write("Largest LTP: %d\n", prime);
 	}
-	if( !rtp_found && is_rt_prime(prime) ) {
+	if( !rtp_found && is_trunc_prime(prime, "r") ) {
 	    rtp_found = true;
 	    write("Largest RTP: %d\n", prime);
@@ Line 2,375: / Line 2,348: @@
 	    break;
     }
+}</lang>
-}
+Output:
-</lang>
+<pre>
+Largest LTP: 999907
+Largest RTP: 739399
+</pre>
 =={{header|PL/I}}==