resolve some TODOs

2015/day24/main.go

@@ -1,4 +1,3 @@
-// TODO: pull combinations, multiplying a slice of ints, into algos and mathy packages?
 package main
 
 import (

2017/day17/main.go

@@ -47,8 +47,7 @@ func spinlock(input string, part int) int {
 		}
 		current = current.next
 
-		// progress log for part 2 brute force...
-		// todo optimize this slow pos
+		// progress log for part 2 brute force... this is SLOW
 		if i%1000000 == 0 {
 			log.Println(i, "steps done")
 		}

2019/day18/part1/main.go

@@ -260,7 +260,6 @@ func (graph *Graph) dfsMinmumDistance() int {
 // helper function to generate a cache string key
 // cache string is of the form entryKey:allKeysToFind
 func makeCacheKey(entry string, keysFound map[string]bool, totalKeys int) string {
-	// TODO: move this into the graph? to avoid making it 910238190382 times
 	allKeys := make([]string, totalKeys)
 	for i := 0; i < totalKeys; i++ {
 		allKeys[i] = cast.ASCIIIntToChar(int('a') + i)