Pandigital prime: Difference between revisions

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 =={{header|Ring}}==
-<lang ring>
+<lang ring>see "working..." + nl
+for z = 1 to 0 step -1
-load "stdlib.ring"
+    see "The largest " + z + "..7 pandigital prime is "
-see "working..." + nl
+    hi = 7654321
-see "The largest pandigital prime is:" + nl
+    if z = 0
+        hi = 76543201
-pand = 0
-limit = 7654321
-for n = limit to 2 step -2
-    flag = 1
-    strn = string(n)
-    if isprime(n)
-       for m = 1 to len(strn)
-           ind = count(strn,string(m))
-           if ind != 1
-              flag = 0
-           ok
-       next
-       if flag = 1
-          pand = n
-          exit
-       ok
     ok
+    for n = hi to 0 step -18
+        strn = string(n)
+        pandig = true
+        for i = z to 7
+            if substr(strn, string(i)) = 0
+                pandig = false
+                exit
+            ok
+        next
+        if pandig and isprime(n)
+            see "" + n + nl
+            exit
+        ok
+    next
 next
+see "done..."
+func isprime(n)
-see "" + pand + nl
+    if n % 3 = 0
+        return false
-see "done..." + nl
+    ok
+    i = 5
-func count(cString,dString)
-     sum = 0
+    while i * i < n
+        if n % i = 0
-     while substr(cString,dString) > 0
-           sum++
+            return false
+        ok
-           cString = substr(cString,substr(cString,dString)+len(string(sum)))
-     end
+        i += 2
-     return sum
+    end
-</lang>
+    return true</lang>
 {{out}}
 <pre>
+working...
-The largest pandigital prime is:
+The largest 1..7 pandigital prime is 7652413
-,652,413
+The largest 0..7 pandigital prime is 76540231
+done...
 </pre>