and cheated just a little to find out how to skip ahead using coprimes

13/main.go

@@ -72,14 +72,17 @@ func partTwo() {
 		}
 	}
 
-	// walking the list works fine for the small test inputs but takes far too long on the real schedule
 	t := float64(0)
+	offset := buses[0].route
 	for {
 	loop:
-		t = t + buses[0].route
+		t = t + offset
+		offset = 1
 		for i := range buses {
 			if math.Remainder(t+buses[i].offset, buses[i].route) != 0 {
 				goto loop
+			} else {
+				offset = offset * buses[i].route
 			}
 		}
 		break