Limit MTC calculation to < 2^32

This ensures the output can fit into a uint64.  Also, calculating it at
this stage is slow, and not calculating it can make the program nearly
instant even for very large numbers!

1 files changed, 4 insertions, 4 deletions

diff --git a/factors/mtc.go b/factors/mtc.go
index d008ca3..522a35c 100644
--- a/factors/mtc.go
+++ b/factors/mtc.go
@@ -3,15 +3,15 @@ package factors
 // MTC returns the multiplication table complexity of a radix n.
 // This is an estimate of how difficult it is to learn a radix's
 // multiplication table.
-func MTC(n uint) uint {
-	mtc := uint(0)
-	for i := uint(2); i <= n - 2; i++ {
+func MTC(n uint64) uint64 {
+	mtc := uint64(0)
+	for i := uint64(2); i <= n - 2; i++ {
 		mtc += n / gcd(i, n)
 	}
 	return mtc
 }
 
-func gcd(a, b uint) uint {
+func gcd(a, b uint64) uint64 {
 	for b > 0 {
 		a, b = b, a % b
 	}