Data commit

Task/Amicable-pairs/BCPL/amicable-pairs.bcpl

@@ -0,0 +1,30 @@
+get "libhdr"
+
+manifest $(
+    MAXIMUM = 20000
+$)
+
+// Calculate proper divisors for 1..N
+let propDivSums(n) = valof
+$(  let v = getvec(n)
+    for i = 1 to n do v!i := 1
+    for i = 2 to n/2 do
+    $(  let j = i*2
+        while j < n do
+        $(  v!j := v!j + i
+            j := j + i
+        $)
+    $)
+    resultis v
+$)
+
+// Are A and B an amicable pair, given the list of sums of proper divisors?
+let amicable(pdiv, a, b) = a = pdiv!b & b = pdiv!a
+
+let start() be
+$(  let pds = propDivSums(MAXIMUM)
+    for x = 1 to MAXIMUM do
+        for y = x+1 to MAXIMUM do
+            if amicable(pds, x, y) do
+                writef("%N, %N*N", x, y)
+$)