use a non brute force approach for day 6

2021/06_test.odin

@@ -18,21 +18,21 @@ d06p1 :: proc(t: ^testing.T) {
 	free_all()
 }
 
-//@(test)
-//d06p2 :: proc(t: ^testing.T) {
-//	input := "3,4,3,1,2"
-//
-//	want := 26984457539
-//	got := simulate_lanterfish_growth(input, 256)
-//	testing.expect(t, got == want, fmt.tprintf("Got: %v | Want: %v", got, want))
-//
-//	free_all()
-//}
+@(test)
+d06p2 :: proc(t: ^testing.T) {
+	input := "3,4,3,1,2"
+
+	want := 26984457539
+	got := simulate_lanterfish_growth(input, 256)
+	testing.expect(t, got == want, fmt.tprintf("Got: %v | Want: %v", got, want))
+
+	free_all()
+}
 
 @(test)
 test_parse_laternfish :: proc(t: ^testing.T) {
 	input := "3,4,3,1,2"
-	want := [dynamic]int{3, 4, 3, 1, 2}
+	want := [9]int{0, 1, 1, 2, 1, 0, 0, 0, 0}
 	got := parse_lanterfish(input)
 
 	for fish, i in got {
@@ -44,8 +44,8 @@ test_parse_laternfish :: proc(t: ^testing.T) {
 
 @(test)
 test_simulate_laternfish_day :: proc(t: ^testing.T) {
-	fish := [dynamic]int{2, 3, 2, 0, 1}
-	want := [dynamic]int{1, 2, 1, 6, 0, 8}
+	fish := [9]int{1, 1, 2, 1, 0, 0, 0, 0, 0}
+	want := [9]int{1, 2, 1, 0, 0, 0, 1, 0, 1}
 
 	simulate_lanternfish_day(&fish)
 

2021/06p1.odin

@@ -17,30 +17,40 @@ D06P1 :: proc() {
 
 simulate_lanterfish_growth :: proc(input: string, days: int) -> int {
 	fish := parse_lanterfish(input)
-	defer delete(fish)
 
 	for _ in 1 ..= days {
 		simulate_lanternfish_day(&fish)
 	}
-	return len(fish)
+
+	total_lanternfish := 0
+	for i in 0 ..< len(fish) {
+		total_lanternfish += fish[i]
+	}
+	return total_lanternfish
 }
 
-parse_lanterfish :: proc(input: string) -> (fish: [dynamic]int) {
+parse_lanterfish :: proc(input: string) -> (fish: [9]int) {
 	fish_strs := strings.split(input, ",", context.temp_allocator)
 	for fish_str in fish_strs {
-		append(&fish, strconv.atoi(fish_str))
+		current_fish := strconv.atoi(fish_str)
+		fish[current_fish] += 1
 	}
 	return
 }
 
-simulate_lanternfish_day :: proc(fish: ^[dynamic]int) {
-	for i in 0 ..< len(fish) {
-		switch fish[i] {
+simulate_lanternfish_day :: proc(fish: ^[9]int) {
+	temp_fish := [9]int{}
+	for i := 8; i >= 0; i -= 1 {
+		switch i {
 		case 0:
-			fish[i] = 6
-			append(fish, 9) // append 9 instead of 8 because this fish will always be processed in this day
+			temp_fish[6] += fish[i]
+			temp_fish[8] = fish[i]
 		case:
-			fish[i] -= 1
+			temp_fish[i - 1] = fish[i]
 		}
 	}
+
+	for i := 0; i < 9; i += 1 {
+		fish[i] = temp_fish[i]
+	}
 }

2021/main.odin

@@ -22,7 +22,7 @@ solutions: map[string]proc() = {
 	"05P1:Hydrothermal Venture" = D05P1,
 	"05P2:Hydrothermal Venture" = D05P2,
 	"06P1:Lanternfish"          = D06P1,
-	//"06P2:Lanternfish"          = D06P2,
+	"06P2:Lanternfish"          = D06P2,
 }
 
 main :: proc() {