Data commit

Task/Additive-primes/Jq/additive-primes-1.jq

@@ -0,0 +1,32 @@
+def is_prime:
+  . as $n
+  | if ($n < 2)         then false
+    elif ($n % 2 == 0)  then $n == 2
+    elif ($n % 3 == 0)  then $n == 3
+    elif ($n % 5 == 0)  then $n == 5
+    elif ($n % 7 == 0)  then $n == 7
+    elif ($n % 11 == 0) then $n == 11
+    elif ($n % 13 == 0) then $n == 13
+    elif ($n % 17 == 0) then $n == 17
+    elif ($n % 19 == 0) then $n == 19
+    else {i:23}
+    | until( (.i * .i) > $n or ($n % .i == 0); .i += 2)
+    | .i * .i > $n
+    end;
+
+# Emit an array of primes less than `.`
+def primes:
+  if . < 2 then []
+  else [2] + [range(3; .; 2) | select(is_prime)]
+  end;
+
+def add(s): reduce s as $x (null; . + $x);
+
+def sumdigits: add(tostring | explode[] | [.] | implode | tonumber);
+
+# Pretty-printing
+def nwise($n):
+  def n: if length <= $n then . else .[0:$n] , (.[$n:] | n) end;
+  n;
+
+def lpad($len): tostring | ($len - length) as $l | (" " * $l)[:$l] + .;

Task/Additive-primes/Jq/additive-primes-2.jq

@@ -0,0 +1,16 @@
+# Input: a number n
+# Output: an array of additive primes less than n
+def additive_primes:
+  primes
+  | . as $primes
+  | reduce .[] as $p (null;
+      ( $p | sumdigits ) as $sum
+      | if (($primes | bsearch($sum)) > -1)
+        then . + [$p]
+        else .
+        end );
+
+"Erdős primes under 500:",
+(500 | additive_primes
+ | ((nwise(10) | map(lpad(4)) | join(" ")),
+   "\n\(length) additive primes found."))