YAPC::EU 2018 Glasgow Update!

Task/Amicable-pairs/Befunge/amicable-pairs.bf

@@ -0,0 +1,6 @@
+v_@#-*8*:"2":$_:#!2#*8#g*#6:#0*#!:#-*#<v>*/.55+,
+1>$$:28*:*:*%\28*:*:*/`06p28*:*:*/\2v %%^:*:<>*v
++|!:-1g60/*:*:*82::+**:*:<<>:#**#8:#<*^>.28*^8 :
+:v>>*:*%/\28*:*:*%+\v>8+#$^#_+#`\:#0<:\`1/*:*2#<
+2v^:*82\/*:*:*82:::_v#!%%*:*:*82\/*:*:*82::<_^#<
+>>06p:28*:*:**1+01-\>1+::28*:*:*/\28*:*:*%:*\`!^

Task/Amicable-pairs/Elena/amicable-pairs-2.elena

@@ -0,0 +1,33 @@
+import extensions.
+import system'routines'stex.
+import system'math.
+import system'collections.
+
+const int Limit = 20000.
+
+extension op
+{
+    properDivisors
+        = Range new(1,self / 2); filterBy(:n)<int,bool>(self mod:n == 0).
+
+    amicablePairs
+    [
+        auto divsums := List<int>(Range new(0, self); selectBy(:i)<int,int>(i properDivisors; summarize)).
+
+        ^ Range from:1 till(divsums length);
+            filterBy(:i)<int,bool>
+            [
+                var sum := divsums[i].
+                ^ (i < sum) && (sum < divsums length) && (divsums[sum] == i)
+            ];
+            selectBy(:i)<int,Tuple<int,int>>(Tuple<int,int>(i,divsums[i])).
+    ]
+}
+
+public program
+[
+    Limit amicablePairs; forEach(:pair)<Tuple<int,int>>
+    [
+        console printLine(pair item1, " ", pair item2).
+    ]
+]