2017 Day 16 & Day 17 Complete

2017/day16/day16.go

@@ -15,24 +15,33 @@ func main() {
 	iters := 1000000000
 	if len(os.Args) > 1 {
 		length = Atoi(os.Args[1])
+		if len(os.Args) > 2 {
+			iters = Atoi(os.Args[2])
+		}
 	}
+
+	// Create a starting string
 	for i := 0; i < length; i++ {
 		progs += string('a' + i)
 	}
+
 	inp := StdinToString()
 	moves := strings.Split(inp, ",")
-	for i := 0; i < iters; i++ {
-		if i%(iters/100) == 0 {
-			// Clear the screen
-			fmt.Print("\033[H\033[2J")
-			// Percent Complete
-			fResult := ((float64(i) / float64(iters)) * 100)
-			sResult2 := strconv.FormatFloat(fResult, 'f', 2, 64)
-			fmt.Println(sResult2)
+
+	var loopEnd int
+	var state []string
+	doneProgs := progs
+	state = append(state, progs)
+	for loopEnd = 1; loopEnd < (iters / 2); loopEnd++ {
+		doneProgs = doDance(doneProgs, moves)
+		state = append(state, doneProgs)
+		if doneProgs == progs {
+			fmt.Println("Loops at", loopEnd)
+			pos := (iters / loopEnd) * loopEnd
+			fmt.Println("Final State", state[iters-pos])
+			break
 		}
-		progs = doDance(progs, moves)
 	}
-	fmt.Println(progs)
 }
 
 func doDance(progs string, moves []string) string {

2017/day16/problem

@@ -0,0 +1,78 @@
+Advent of Code
+
+--- Day 16: Permutation Promenade ---
+
+   You come upon a very unusual sight; a group of programs here appear to be
+   dancing.
+
+   There are sixteen programs in total, named a through p. They start by
+   standing in a line: a stands in position 0, b stands in position 1, and so on
+   until p, which stands in position 15.
+
+   The programs' dance consists of a sequence of dance moves:
+
+     * Spin, written sX, makes X programs move from the end to the front, but
+       maintain their order otherwise. (For example, s3 on abcde produces
+       cdeab).
+     * Exchange, written xA/B, makes the programs at positions A and B swap
+       places.
+     * Partner, written pA/B, makes the programs named A and B swap places.
+
+   For example, with only five programs standing in a line (abcde), they could
+   do the following dance:
+
+     * s1, a spin of size 1: eabcd.
+     * x3/4, swapping the last two programs: eabdc.
+     * pe/b, swapping programs e and b: baedc.
+
+   After finishing their dance, the programs end up in order baedc.
+
+   You watch the dance for a while and record their dance moves (your puzzle
+   input). In what order are the programs standing after their dance?
+
+   Your puzzle answer was ________________.
+
+--- Part Two ---
+
+   Now that you're starting to get a feel for the dance moves, you turn your
+   attention to the dance as a whole.
+
+   Keeping the positions they ended up in from their previous dance, the
+   programs perform it again and again: including the first dance, a total of
+   one billion (1000000000) times.
+
+   In the example above, their second dance would begin with the order baedc,
+   and use the same dance moves:
+
+     * s1, a spin of size 1: cbaed.
+     * x3/4, swapping the last two programs: cbade.
+     * pe/b, swapping programs e and b: ceadb.
+
+   In what order are the programs standing after their billion dances?
+
+   Your puzzle answer was ________________.
+
+   Both parts of this puzzle are complete! They provide two gold stars: **
+
+   At this point, you should return to your advent calendar and try another
+   puzzle.
+
+   If you still want to see it, you can get your puzzle input.
+
+References
+
+   Visible links
+   . http://adventofcode.com/
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+   . http://adventofcode.com/2017/sponsors
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017/day/16/input