after pull

2024/go/day20/day20.go

@@ -52,14 +52,54 @@ func Part1(input string) int {
 	return dist
 }
 func Part2(input string) int {
+	const saves int = 100
+	count := 0
 	maze := Maze{}.Parse(input)
-	fmt.Println(maze)
+	//	fmt.Println(maze)
 	data := inputGraph(*maze)
 	graph := dijkstra.CreateGraph(data)
-	_, count := dijkstra.GetShortestPath(data.From, data.To, graph)
+	path, dist := dijkstra.GetShortestPath(data.From, data.To, graph)
+	cost := make(map[Vec]int)
+	cheats := []Cheat{}
+
+	for i, p := range path {
+		cost[Vec{p.X, p.Y}] = i
+	}
+	cheat_data := cheatGraph(*maze)
+
+	for _, s := range path[:len(path)-saves] {
+		fmt.Println("Checking start:", s)
+		for _, e := range path[saves:] {
+			fmt.Println("\tChecking end", e)
+			cheat_data_1 := cheatGraphAdd(maze, cheat_data, s)
+			cheat_data_2 := cheatGraphAdd(maze, cheat_data_1, e)
+			cheat_graph := dijkstra.CreateGraph(cheat_data_2)
+			_, cheat_dist := dijkstra.GetShortestPath(dijkstra.Point{X: s.X, Y: s.Y}, dijkstra.Point{X: e.X, Y: e.Y}, cheat_graph)
+			fmt.Println("\t\tcheat distance:", cheat_dist)
+			if cheat_dist <= 20 {
+				cheat := Cheat{start: Vec{s.X, s.Y}, end: Vec{e.X, e.Y}, cost: cost[Vec{s.X, s.Y}] + cheat_dist + dist - cost[Vec{e.X, e.Y}]}
+				fmt.Println("\t\tSaving cheat:", cheat)
+				cheats = append(cheats, cheat)
+			}
+		}
+	}
+	for _, cheat := range cheats {
+		save := dist - cheat.cost
+		//		fmt.Println("[", i, "]", "save", save)
+		if save >= saves {
+			count++
+		}
+	}
 	return count
 }
 
+func abs(in int) int {
+	if in < 0 {
+		return in * -1
+	}
+	return in
+}
+
 func inputGraph(maze Maze) dijkstra.InputGraph {
 	data := dijkstra.InputGraph{}
 	data.From = dijkstra.Point{X: maze.start.x, Y: maze.start.y}
@@ -89,6 +129,58 @@ func inputGraph(maze Maze) dijkstra.InputGraph {
 	return data
 }
 
+func cheatGraph(maze Maze) dijkstra.InputGraph {
+	data := dijkstra.InputGraph{}
+	for y := 0; y < maze.height; y++ {
+		for x := 0; x < maze.width; x++ {
+			if maze.grid.Get(x, y) == CORRIDOR {
+				continue
+			}
+			for _, dir := range DIRECTIONS {
+				nx, ny := x+dir.x, y+dir.y
+				if nx < 0 || ny < 0 || nx >= maze.width || ny >= maze.height {
+					continue
+				}
+				if maze.grid.Get(nx, ny) == CORRIDOR {
+					continue
+				}
+				data.Graph = append(data.Graph, dijkstra.InputData{
+					Source:      dijkstra.Point{X: x, Y: y},
+					Destination: dijkstra.Point{X: nx, Y: ny},
+					Weight:      1,
+				})
+			}
+		}
+	}
+
+	return data
+}
+
+func cheatGraphAdd(maze *Maze, in dijkstra.InputGraph, s dijkstra.Point) dijkstra.InputGraph {
+	x := s.X
+	y := s.Y
+	out := dijkstra.InputGraph{}
+	out.From = in.From
+	out.To = in.To
+	out.Graph = append([]dijkstra.InputData{}, in.Graph...)
+
+	for _, dir := range DIRECTIONS {
+		nx, ny := x+dir.x, y+dir.y
+		if nx < 0 || ny < 0 || nx >= maze.width || ny >= maze.height {
+			continue
+		}
+		if maze.grid.Get(nx, ny) == CORRIDOR {
+			continue
+		}
+		out.Graph = append(out.Graph, dijkstra.InputData{
+			Source:      dijkstra.Point{X: x, Y: y},
+			Destination: dijkstra.Point{X: nx, Y: ny},
+			Weight:      1,
+		})
+	}
+	return out
+}
+
 func (m Maze) Parse(input string) *Maze {
 	m.grid = inputs.ToGrid2D(input, "\n", "", '?', func(c string) Cell { return Cell(c[0]) })
 	m.height, m.width = m.grid.SizeY(), m.grid.SizeX()

2024/go/day20/day20_test.go

@@ -26,6 +26,20 @@ func TestPart1(t *testing.T) {
 }
 
 func TestPart2(t *testing.T) {
-	r := Part2("")
+	r := Part2(`###############
+#...#...#.....#
+#.#.#.#.#.###.#
+#S#...#.#.#...#
+#######.#.#.###
+#######.#.#...#
+#######.#.###.#
+###..E#...#...#
+###.#######.###
+#...###...#...#
+#.#####.#.###.#
+#.#...#.#.#...#
+#.#.#.#.#.#.###
+#...#...#...###
+###############`)
 	require.Equal(t, 0, r)
 }

2024/go/day21/day21.go

@@ -0,0 +1,181 @@
+package day21
+
+import (
+	"adventofcode2024/utils"
+	"adventofcode2024/utils/dijkstra"
+	"adventofcode2024/utils/memo"
+	"fmt"
+	"math"
+	"strings"
+)
+
+type Pair struct {
+	s dijkstra.Point
+	d dijkstra.Point
+}
+
+type Path struct {
+	path     []dijkstra.Point
+	path_str string
+	cost     int
+}
+
+type State struct {
+	code         string
+	depth        int
+	isNumericPad bool
+}
+
+var numericPad = map[dijkstra.Point]string{
+	{X: 0, Y: 0}: "7", {X: 1, Y: 0}: "8", {X: 2, Y: 0}: "9",
+	{X: 0, Y: 1}: "4", {X: 1, Y: 1}: "5", {X: 2, Y: 1}: "6",
+	{X: 0, Y: 2}: "1", {X: 1, Y: 2}: "2", {X: 2, Y: 2}: "3",
+	{X: 1, Y: 3}: "0", {X: 2, Y: 3}: "A",
+}
+
+var directionPad = map[dijkstra.Point]string{
+	{X: 1, Y: 0}: "^", {X: 2, Y: 0}: "A",
+	{X: 0, Y: 1}: "<", {X: 1, Y: 1}: "v", {X: 2, Y: 1}: ">",
+}
+
+var directions = []dijkstra.Point{{X: 0, Y: 1}, {X: 0, Y: -1}, {X: 1, Y: 0}, {X: -1, Y: 0}}
+
+var lookup_np = get_paths(numericPad)
+var lookup_dp = get_paths(directionPad)
+
+var m *memo.Memo
+
+func init() {
+	m = memo.New(get_shortest_path)
+}
+
+func Part1(input string) int {
+	codes := strings.Split(input, "\n")
+	cost := 0
+	for _, code := range codes {
+		initialState := State{
+			code:         code,
+			depth:        2,
+			isNumericPad: true,
+		}
+		result := m.Get(initialState).(int)
+		cost += result * utils.MustAtoi(code[:len(code)-1])
+	}
+	return cost
+}
+
+func Part2(input string) int {
+	codes := strings.Split(input, "\n")
+	cost := 0
+	for _, code := range codes {
+		initialState := State{
+			code:         code,
+			depth:        25,
+			isNumericPad: true,
+		}
+		result := m.Get(initialState).(int)
+		cost += result * utils.MustAtoi(code[:len(code)-1])
+	}
+	return cost
+}
+
+func get_paths(in map[dijkstra.Point]string) map[Pair][]Path {
+	lookup := make(map[Pair][]Path)
+	data := dijkstra.InputGraph{}
+	for p := range in {
+		for _, dir := range directions {
+			np := dijkstra.Point{X: p.X + dir.X, Y: p.Y + dir.Y}
+			if in[np] != "" {
+				data.Graph = append(data.Graph, dijkstra.InputData{
+					Source:      p,
+					Destination: np,
+					Weight:      1,
+				})
+			}
+		}
+	}
+	graph := dijkstra.CreateGraph(data)
+	for s := range in {
+		for d := range in {
+			paths, cost := dijkstra.GetAllShortestPaths(s, d, graph)
+
+			for _, path := range paths {
+				path_str := ""
+				for x := 1; x < len(path); x++ {
+					f := path[x-1]
+					t := path[x]
+
+					switch {
+					case f.X == t.X && f.Y < t.Y:
+						// Moving verticallY down
+						path_str += "v"
+					case f.X == t.X && f.Y > t.Y:
+						// Moving verticallY up
+						path_str += "^"
+					case f.Y == t.Y && f.X < t.X:
+						// Moving horizontallY right
+						path_str += ">"
+					case f.Y == t.Y && f.X > t.X:
+						// Moving horizontally left
+						path_str += "<"
+					default:
+						// No matching case or invalid input
+						fmt.Println("Invalid direction")
+					}
+
+				}
+				lookup[Pair{s, d}] = append(lookup[Pair{s, d}], Path{path, path_str, cost})
+			}
+
+		}
+	}
+	return lookup
+}
+
+func find_point(in string, lookup map[dijkstra.Point]string) dijkstra.Point {
+	for k, v := range lookup {
+		if v == in {
+			return k
+		}
+	}
+	return dijkstra.Point{}
+}
+
+func get_shortest_path(key interface{}) interface{} {
+	state := key.(State)
+
+	if state.depth < 0 {
+		return len(state.code)
+	}
+
+	// (Optional) If you need to modify the state, work on a copy.
+	newState := state
+	newState.code = "A" + state.code
+
+	cost := 0
+	for x := 0; x<len(newState.code)-1; x++ {
+		pps := shortest_paths(string(newState.code[x]), string(newState.code[x+1]), newState.isNumericPad)
+		min := math.MaxInt // Start with a very high number not just 65535
+		for _, pp := range pps {
+			nextState := State{
+				code:         pp.path_str + "A",
+				depth:        newState.depth - 1,
+				isNumericPad: false,
+			}
+			mm := m.Get(nextState).(int)
+			if mm < min {
+				min = mm
+			}
+		}
+		cost += min
+	}
+	return cost
+}
+
+func shortest_paths(s, d string, isNumericPad bool) []Path {
+	if isNumericPad {
+		return lookup_np[Pair{s: find_point(s, numericPad), d: find_point(d, numericPad)}]
+	} else {
+		return lookup_dp[Pair{s: find_point(s, directionPad), d: find_point(d, directionPad)}]
+	}
+}

2024/go/day21/day21_test.go

@@ -0,0 +1,25 @@
+package day21
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestPart1(t *testing.T) {
+	r := Part1(`029A
+980A
+179A
+456A
+379A`)
+	require.Equal(t, 126384, r)
+}
+
+func TestPart2(t *testing.T) {
+	r := Part2(`029A
+980A
+179A
+456A
+379A`)
+	require.Equal(t, 126384, r)
+}

2024/go/day21/input.txt

@@ -0,0 +1,5 @@
+480A
+965A
+140A
+341A
+285A

2024/go/day21/tt

@@ -0,0 +1,9 @@
+
+v<A <A A >>^A v<<A>A<A>>^AvAA<^A>AvA<^A>vA^A
+<vA <A A >>^A vA A <^A >A      <v<A>>^AvA^A<vA>^A<v<A>^A>AAvA^A<v<A>A>^AAAvA<^A>A
+  v  < <    A  > >   ^  A      <A>AvA<^AA>A<vAAA>^A
+            <           A                            ^A>^^AvvvA
+0                              29A
+
+
+

2024/go/day22/day22.go

@@ -0,0 +1,91 @@
+package day22
+
+import (
+	"adventofcode2024/utils"
+	rb "adventofcode2024/utils/ringbuffer"
+	"strconv"
+	"strings"
+)
+
+func Part1(input string) int {
+	var secret uint
+	total := 0
+	secrets := strings.Split(input, "\n")
+	for _, secret_str := range secrets {
+		secret = uint(utils.MustAtoi(secret_str))
+		for i := 0; i < 2000; i++ {
+			secret ^= secret * 64
+			secret %= 16777216
+			secret ^= secret / 32
+			secret %= 16777216
+			secret ^= secret * 2048
+			secret %= 16777216
+		}
+		total += int(secret)
+	}
+	return total
+}
+
+func Part2(input string) int {
+	var secret uint
+	var banannas0, banannas1, banannas2, banannas3, banannas4 int
+	seq_map := make(map[string]int)
+	total := 0
+	ringBuffer := rb.NewRingBuffer[uint](5)
+
+	secrets := strings.Split(input, "\n")
+	for _, secret_str := range secrets {
+		found_map := make(map[string]bool)
+		secret = uint(utils.MustAtoi(secret_str))
+		for i := 0; i < 2000; i++ {
+			secret = get_next_secret(secret)
+			ringBuffer.Add(secret)
+			if ringBuffer.Len() < 5 { continue }
+			ring := ringBuffer.Get()
+			banannas0 = get_bannnas(ring[0])
+			banannas1 = get_bannnas(ring[1])
+			banannas2 = get_bannnas(ring[2])
+			banannas3 = get_bannnas(ring[3])
+			banannas4 = get_bannnas(ring[4])
+			map_str := diff_bannanas(banannas1, banannas0) +
+				diff_bannanas(banannas2, banannas1) +
+				diff_bannanas(banannas3, banannas2) +
+				diff_bannanas(banannas4, banannas3)
+			if _, ok := found_map[map_str]; !ok {
+				seq_map[map_str] += banannas4
+				found_map[map_str] = true
+			}
+		}
+	}
+	for _, v := range seq_map {
+		if v > total {
+			total = v
+		}
+	}
+	return total
+}
+
+func get_next_secret(in uint) uint {
+	in ^= in * 64
+	in %= 16777216
+	in ^= in / 32
+	in %= 16777216
+	in ^= in * 2048
+	in %= 16777216
+	return in
+}
+
+func get_bannnas(secret uint) int {
+	return int(secret) % 10
+}
+
+func diff_bannanas(a, b int) string {
+	ret := ""
+	diff := a - b
+	if diff >= 0 {
+		ret = "+" + strconv.Itoa(diff)
+	} else {
+		ret = strconv.Itoa(diff)
+	}
+	return ret
+}

2024/go/day22/day22_test.go

@@ -0,0 +1,20 @@
+package day22
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestPart1(t *testing.T) {
+	r := Part1("1")
+	require.Equal(t, 8685429, r)
+}
+
+func TestPart2(t *testing.T) {
+	r := Part2(`1
+2
+3
+2024`)
+	require.Equal(t, 23, r)
+}

2024/go/day23/day23.go

@@ -0,0 +1,242 @@
+package day23
+
+import (
+	"fmt"
+	"regexp"
+	"sort"
+	"strings"
+)
+
+type Lan struct {
+	nodes []*Node
+}
+
+type Node struct {
+	key      string
+	adjacent []*Node
+	loops    [][]*Node
+}
+
+func Part1(input string) int {
+	total := 0
+
+	lan := &Lan{}
+
+	pattern := `^([a-z]{2})-([a-z]{2})$`
+	re := regexp.MustCompile(pattern)
+	lines := strings.Split(input, "\n")
+	for _, line := range lines {
+		matches := re.FindAllStringSubmatch(line, -1)
+		for _, match := range matches {
+			lan.AddNode(match[1])
+			lan.AddNode(match[2])
+			lan.AddConnection(match[1], match[2])
+			lan.AddConnection(match[2], match[1])
+		}
+	}
+	for _, node := range lan.nodes {
+		if node.key[0] == 't' {
+			connections := node.adjacent
+			for _, connection := range connections {
+				c := lan.getNode(connection.key)
+				for _, n1 := range c.adjacent {
+					for _, n2 := range connections {
+						if n1.key == n2.key {
+							already_found := false
+							for _, loop := range node.loops {
+								if contains(loop, c.key) && contains(loop, n2.key) {
+									already_found = true
+									break
+								}
+							}
+
+							for _, loop := range c.loops {
+								if contains(loop, node.key) && contains(loop, n2.key) {
+									already_found = true
+									break
+								}
+							}
+
+							for _, loop := range n2.loops {
+								if contains(loop, c.key) && contains(loop, node.key) {
+									already_found = true
+									break
+								}
+							}
+
+							if !already_found {
+								already_found = true
+								total++
+								loop := make([]*Node, 0)
+								loop = append(loop, node)
+								loop = append(loop, c)
+								loop = append(loop, n2)
+								node.loops = append(node.loops, loop)
+								fmt.Printf("%v,%v,%v\n", node.key, c.key, n2.key)
+							}
+						}
+					}
+				}
+			}
+		}
+	}
+	lan.Print()
+	t := 0
+	for _, node := range lan.nodes {
+		if node.key[0] == 't' {
+			t += len(node.loops)
+			fmt.Printf("Node: %v\n", node.key)
+			for _, loop := range node.loops {
+				for _, n := range loop {
+					fmt.Printf(" %v ", n.key)
+				}
+				fmt.Println()
+			}
+		}
+	}
+	fmt.Printf("Total: %d\n", t)
+	return total
+}
+
+func Part2(input string) int {
+	total := 0
+
+	lan := &Lan{}
+
+	pattern := `^([a-z]{2})-([a-z]{2})$`
+	re := regexp.MustCompile(pattern)
+	lines := strings.Split(input, "\n")
+	for _, line := range lines {
+		matches := re.FindAllStringSubmatch(line, -1)
+		for _, match := range matches {
+			lan.AddNode(match[1])
+			lan.AddNode(match[2])
+			lan.AddConnection(match[1], match[2])
+			lan.AddConnection(match[2], match[1])
+		}
+	}
+	for _, node := range lan.nodes {
+		connections := node.adjacent
+		for _, connection := range connections {
+			c := lan.getNode(connection.key)
+			for _, n1 := range c.adjacent {
+				for _, n2 := range connections {
+					if n1.key == n2.key {
+						already_found := false
+						for _, loop := range node.loops {
+							if contains(loop, c.key) && contains(loop, n2.key) {
+								already_found = true
+								break
+							}
+						}
+
+						for _, loop := range c.loops {
+							if contains(loop, node.key) && contains(loop, n2.key) {
+								already_found = true
+								break
+							}
+						}
+
+						for _, loop := range n2.loops {
+							if contains(loop, c.key) && contains(loop, node.key) {
+								already_found = true
+								break
+							}
+						}
+
+						if !already_found {
+							already_found = true
+							total++
+							loop := make([]*Node, 0)
+							loop = append(loop, node)
+							loop = append(loop, c)
+							loop = append(loop, n2)
+							node.loops = append(node.loops, loop)
+							fmt.Printf("%v,%v,%v\n", node.key, c.key, n2.key)
+						}
+					}
+				}
+			}
+		}
+	}
+	lan.Print()
+	maxLoop := 0
+	var maxNode *Node
+	for _, node := range lan.nodes {
+		if len(node.loops) > maxLoop {
+			maxLoop = len(node.loops)
+			maxNode = node
+		}
+	}
+	fmt.Printf("Max: %d\n", len(maxNode.loops))
+	nodeList := make([]*Node, 0)
+	keyList := make([]string, 0)
+	for _, loop := range maxNode.loops {
+		for _, l := range loop {
+			if !contains(nodeList, l.key) {
+				nodeList = append(nodeList, l)
+				keyList = append(keyList, l.key)
+			}
+		}
+	}
+	sort.Strings(keyList)
+	fmt.Println(strings.Join(keyList, ","))
+	return len(nodeList)
+}
+
+func (g *Lan) AddNode(key string) {
+	if !contains(g.nodes, key) {
+		g.nodes = append(g.nodes, &Node{key: key})
+	}
+}
+
+func (g *Lan) AddConnection(from, to string) {
+	fromNode := g.getNode(from)
+	toNode := g.getNode(to)
+
+	if fromNode == nil || toNode == nil {
+		err := fmt.Errorf("Error: Invalid edge (%v --> %v)", from, to)
+		fmt.Println(err.Error())
+	} else if contains(fromNode.adjacent, to) {
+		err := fmt.Errorf("Error: Existing edge (%v --> %v)", from, to)
+		fmt.Println(err.Error())
+	} else {
+		fromNode.adjacent = append(fromNode.adjacent, toNode)
+	}
+}
+
+func (g *Lan) getNode(key string) *Node {
+	for i, v := range g.nodes {
+		if v.key == key {
+			return g.nodes[i]
+		}
+	}
+	return nil
+}
+
+func (g *Lan) Print() {
+	for _, v := range g.nodes {
+		fmt.Printf("\nNode %v : ", v.key)
+		for _, v := range v.adjacent {
+			fmt.Printf(" %v ", v.key)
+		}
+		fmt.Println()
+		for _, loop := range v.loops {
+			for _, v := range loop {
+				if v != nil {
+					fmt.Printf(" %v ", v.key)
+				}
+			}
+			fmt.Println()
+		}
+	}
+}
+
+func contains(list []*Node, key string) bool {
+	for _, v := range list {
+		if key == v.key {
+			return true
+		}
+	}
+	return false
+}

2024/go/day23/day23_test.go

@@ -0,0 +1,79 @@
+package day23
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestPart1(t *testing.T) {
+	r := Part1(`kh-tc
+qp-kh
+de-cg
+ka-co
+yn-aq
+qp-ub
+cg-tb
+vc-aq
+tb-ka
+wh-tc
+yn-cg
+kh-ub
+ta-co
+de-co
+tc-td
+tb-wq
+wh-td
+ta-ka
+td-qp
+aq-cg
+wq-ub
+ub-vc
+de-ta
+wq-aq
+wq-vc
+wh-yn
+ka-de
+kh-ta
+co-tc
+wh-qp
+tb-vc
+td-yn`)
+	require.Equal(t, 7, r)
+}
+
+func TestPart2(t *testing.T) {
+	r := Part2(`kh-tc
+qp-kh
+de-cg
+ka-co
+yn-aq
+qp-ub
+cg-tb
+vc-aq
+tb-ka
+wh-tc
+yn-cg
+kh-ub
+ta-co
+de-co
+tc-td
+tb-wq
+wh-td
+ta-ka
+td-qp
+aq-cg
+wq-ub
+ub-vc
+de-ta
+wq-aq
+wq-vc
+wh-yn
+ka-de
+kh-ta
+co-tc
+wh-qp
+tb-vc
+td-yn`)
+	require.Equal(t, "co,de,ka,ta", r)
+}

2024/go/day24/day24.go

@@ -0,0 +1,297 @@
+package day24
+
+import (
+	"adventofcode2024/utils"
+	"fmt"
+	"regexp"
+	"sort"
+	"strings"
+)
+
+type Network struct {
+	gates []*Gate
+	wires []*Wire
+}
+
+type State int
+
+const (
+	NA State = iota - 1
+	ZERO
+	ONE
+)
+
+type Wire struct {
+	name  string
+	state State
+}
+
+type Operation int
+
+const (
+	AND Operation = iota
+	OR
+	XOR
+)
+
+type Gate struct {
+	in  [2]*Wire
+	out *Wire
+	op  Operation
+}
+
+func Part1(input string) int {
+
+	network := &Network{}
+	network.wires = make([]*Wire, 0)
+
+	data := strings.Split(input, "\n\n")
+
+	network.AddWires(data[0])
+	network.AddGates(data[1])
+	for {
+		if network.OutputKnown() {
+			break
+		}
+		for _, gate := range network.gates {
+			//			fmt.Printf("%d: %v\n", i, gate)
+			if gate.out.state == NA && gate.in[0].state != NA && gate.in[1].state != NA {
+				switch gate.op {
+				case AND:
+					gate.out.state = And(gate.in[0].state, gate.in[1].state)
+				case OR:
+					gate.out.state = Or(gate.in[0].state, gate.in[1].state)
+				case XOR:
+					gate.out.state = Xor(gate.in[0].state, gate.in[1].state)
+				}
+			}
+		}
+	}
+	return int(network.Output())
+}
+
+func Part2(input string) int64 {
+
+	data := strings.Split(input, "\n\n")
+
+	inputs := strings.Split(data[0], "\n")
+	num_inputs := len(inputs) / 2
+	fmt.Println(num_inputs)
+	var x_value int64
+	var y_value int64
+	var z_value int64
+	y_value = 0
+	for i := 0; i < num_inputs; i++ {
+	//	y_value = 1 << i
+		x_value = 1 << i
+		network := &Network{}
+		network.wires = make([]*Wire, 0)
+		network.AddWires2("x", num_inputs, x_value)
+		network.AddWires2("y", num_inputs, y_value)
+		network.AddGates(data[1])
+		//		for i, gate := range network.gates {
+		//			fmt.Printf("%d: %v\n", i, gate)
+		//		}
+		network.SwapOutputs("z07", "rts")
+		network.SwapOutputs("z12", "jpj")
+		network.SwapOutputs("z26", "kgj")
+		network.SwapOutputs("vvw", "chv")
+
+		//		for i, gate := range network.gates {
+		//			fmt.Printf("%d: %v\n", i, gate)
+		//		}
+		for {
+			if network.OutputKnown() {
+				break
+			}
+			for _, gate := range network.gates {
+				//			fmt.Printf("%d: %v\n", i, gate)
+				if gate.out.state == NA && gate.in[0].state != NA && gate.in[1].state != NA {
+					switch gate.op {
+					case AND:
+						gate.out.state = And(gate.in[0].state, gate.in[1].state)
+					case OR:
+						gate.out.state = Or(gate.in[0].state, gate.in[1].state)
+					case XOR:
+						gate.out.state = Xor(gate.in[0].state, gate.in[1].state)
+					}
+				}
+			}
+		}
+		z_value = network.Output()
+		if x_value +  y_value  != z_value {
+			fmt.Printf("(%d):\t x:%4d\t: y:%4d z:%4d\n", i, x_value, y_value, z_value)
+		}
+	}
+	ans := []string{"z07", "rts", "z12", "jpj", "z26", "kgj", "vvw", "chv"}
+	sort.Strings(ans)
+	fmt.Println(strings.Join(ans, ","))
+	return z_value
+}
+
+func (n *Network) AddWires(data string) {
+	for _, line := range strings.Split(data, "\n") {
+		v := strings.Split(line, ": ")
+		n.AddWire(&Wire{name: v[0], state: to_state(v[1])})
+	}
+}
+
+func (n *Network) AddWire(wire *Wire) {
+	n.wires = append(n.wires, wire)
+}
+
+func (n *Network) AddWires2(w string, count int, value int64) {
+	for x := 0; x < count; x++ {
+		name := fmt.Sprintf("%s%02d", w, x)
+		v := fmt.Sprintf("%d", (value>>x)&1)
+		n.AddWire(&Wire{name: name, state: to_state(v)})
+	}
+
+}
+
+func (n *Network) AddGates(data string) {
+	// ntg XOR fgs -> mjb
+	pattern := `^([a-z0-9]{3}) (AND|OR|XOR) ([a-z0-9]{3}) -> ([a-z[0-9]{3})$`
+
+	re := regexp.MustCompile(pattern)
+	for _, line := range strings.Split(data, "\n") {
+		matches := re.FindAllStringSubmatch(line, -1)
+		for _, match := range matches {
+			n.AddGate(match[1], match[2], match[3], match[4], &n.wires)
+		}
+	}
+}
+
+func (n *Network) SwapOutputs(a, b string) {
+	_, wire1 := to_wire(a, n.wires)
+	_, wire2 := to_wire(b, n.wires)
+	for _, gate := range n.gates {
+		if gate.out.name == a {
+			gate.out = wire2
+		} else if gate.out.name == b {
+			gate.out = wire1
+		}
+	}
+}
+
+func (n *Network) AddGate(in0, op, in1, out string, wires *[]*Wire) {
+	var in [2]*Wire
+	var outw *Wire
+	*wires, in[0] = to_wire(in0, *wires)
+	*wires, in[1] = to_wire(in1, *wires)
+	*wires, outw = to_wire(out, *wires)
+	n.gates = append(n.gates, &Gate{in: in,
+		op:  to_operation(op),
+		out: outw})
+}
+
+func (n *Network) OutputKnown() bool {
+	for _, gate := range n.gates {
+		if gate.out.name[0] != 'z' {
+			continue
+		}
+		if gate.out.state == NA {
+			return false
+		}
+	}
+	return true
+}
+
+func (n *Network) Output() int64 {
+	var ret int64
+	ret = 0
+	for _, gate := range n.gates {
+		if gate.out.name[0] != 'z' {
+			continue
+		}
+		addr := utils.MustAtoi(gate.out.name[1:])
+		if gate.out.state == ONE {
+			ret += 1 << addr
+		}
+	}
+	return ret
+}
+
+func (n Gate) String() string {
+	return n.in[0].name + "(" + n.in[0].state.String() + ")\t" + n.op.String() + " " + n.in[1].name + "(" + n.in[1].state.String() + ")\t ->\t" + n.out.name + " (" + n.out.state.String() + ")"
+}
+func to_state(in string) State {
+	switch in {
+	case "1":
+		return ONE
+	case "0":
+		return ZERO
+	}
+	return NA
+}
+
+func to_operation(in string) Operation {
+	var val Operation
+	switch in {
+	case "AND":
+		val = AND
+	case "OR":
+		val = OR
+	case "XOR":
+		val = XOR
+	}
+	return val
+}
+
+func to_wire(in string, wires []*Wire) ([]*Wire, *Wire) {
+	for _, v := range wires {
+		if in == v.name {
+			return wires, v
+		}
+	}
+	wire := Wire{name: in, state: NA}
+	wires = append(wires, &wire)
+	return wires, &wire
+}
+
+func And(a, b State) State {
+	if a == ONE && b == ONE {
+		return ONE
+	}
+	return ZERO
+}
+
+func Or(a, b State) State {
+	if a == ONE || b == ONE {
+		return ONE
+	}
+	return ZERO
+}
+
+func Xor(a, b State) State {
+	if (a == ONE && b == ZERO) || (a == ZERO && b == ONE) {
+		return ONE
+	}
+	return ZERO
+}
+
+func (state State) String() string {
+	switch state {
+	case NA:
+		return "NA"
+	case ZERO:
+		return "0"
+	case ONE:
+		return "1"
+	default:
+		return "Invalid"
+	}
+}
+
+func (op Operation) String() string {
+	switch op {
+	case OR:
+		return "OR"
+	case AND:
+		return "AND"
+	case XOR:
+		return "XOR"
+	default:
+		return "Invalid"
+	}
+}

2024/go/day24/day24_test.go

@@ -0,0 +1,17 @@
+package day24
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestPart1(t *testing.T) {
+	r := Part1("")
+	require.Equal(t, 0, r)
+}
+
+func TestPart2(t *testing.T) {
+	r := Part2("")
+	require.Equal(t, 0, r)
+}

2024/go/day24/input.txt

@@ -0,0 +1,313 @@
+x00: 1
+x01: 0
+x02: 1
+x03: 1
+x04: 0
+x05: 0
+x06: 1
+x07: 1
+x08: 0
+x09: 1
+x10: 1
+x11: 1
+x12: 1
+x13: 0
+x14: 1
+x15: 1
+x16: 1
+x17: 1
+x18: 1
+x19: 1
+x20: 0
+x21: 1
+x22: 0
+x23: 1
+x24: 0
+x25: 1
+x26: 1
+x27: 1
+x28: 1
+x29: 0
+x30: 0
+x31: 1
+x32: 0
+x33: 1
+x34: 1
+x35: 0
+x36: 0
+x37: 1
+x38: 0
+x39: 1
+x40: 1
+x41: 1
+x42: 1
+x43: 0
+x44: 1
+y00: 1
+y01: 0
+y02: 0
+y03: 1
+y04: 1
+y05: 0
+y06: 0
+y07: 0
+y08: 0
+y09: 0
+y10: 0
+y11: 1
+y12: 0
+y13: 1
+y14: 0
+y15: 1
+y16: 1
+y17: 1
+y18: 1
+y19: 0
+y20: 0
+y21: 1
+y22: 1
+y23: 1
+y24: 1
+y25: 0
+y26: 0
+y27: 1
+y28: 1
+y29: 1
+y30: 1
+y31: 0
+y32: 0
+y33: 0
+y34: 1
+y35: 1
+y36: 1
+y37: 0
+y38: 1
+y39: 1
+y40: 1
+y41: 1
+y42: 0
+y43: 1
+y44: 1
+
+x03 AND y03 -> htr
+gwb AND kvf -> pkd
+x04 AND y04 -> jjm
+qcm XOR twv -> z21
+rrq XOR bmp -> z44
+x43 AND y43 -> pnn
+x06 XOR y06 -> qmt
+x26 AND y26 -> z26
+y00 AND x00 -> whb
+jfq XOR fbb -> z36
+y33 AND x33 -> mmb
+x38 AND y38 -> vqt
+bbh OR qtd -> jfq
+cbs AND ttb -> qtd
+wqs OR cmf -> tpf
+x10 AND y10 -> bfm
+djp OR pfb -> qvr
+x20 XOR y20 -> vhb
+kkd XOR cjg -> z32
+qpp XOR stg -> z41
+kkd AND cjg -> mdv
+tpp OR pfj -> twv
+www AND qdf -> vjf
+y15 XOR x15 -> hmr
+mtg XOR sqm -> z09
+x33 XOR y33 -> chc
+x41 AND y41 -> pkj
+x31 AND y31 -> cvn
+x09 AND y09 -> nvw
+mtg AND sqm -> chg
+pkr AND kcv -> thc
+x07 XOR y07 -> cds
+x15 AND y15 -> fpr
+mwv AND jsg -> wdw
+mwv XOR jsg -> z38
+y16 XOR x16 -> svs
+y14 XOR x14 -> fnq
+wth OR vjf -> btv
+bvp AND gdb -> stc
+cjb XOR rjc -> z04
+x13 AND y13 -> pfb
+x30 AND y30 -> qgf
+htq AND rtk -> dsm
+x18 XOR y18 -> kvf
+y12 AND x12 -> mqn
+bcj XOR bkh -> z03
+x07 AND y07 -> sdj
+bdf OR wbw -> qkf
+y30 XOR x30 -> kbn
+tpf AND vhb -> tpp
+hqd OR fpr -> hgh
+vfm XOR hbw -> z23
+x01 AND y01 -> bdf
+nvw OR chg -> vgp
+x21 XOR y21 -> qcm
+bwg AND mfn -> djp
+dnf OR pkj -> ksp
+y44 AND x44 -> gqr
+y11 AND x11 -> smr
+smr OR dsm -> ksn
+jkm OR pkd -> rjf
+thc OR sqt -> rbd
+qvr XOR fnq -> z14
+cjb AND rjc -> fsb
+svg XOR fmt -> z31
+x06 AND y06 -> ssv
+dtj OR vvq -> jvp
+chv XOR fqf -> z34
+cvr AND hck -> pjd
+dqp AND nbm -> hvv
+x29 AND y29 -> vvq
+y13 XOR x13 -> mfn
+ksn AND nft -> z12
+jjd XOR whb -> z01
+chc AND rnq -> vjh
+y36 AND x36 -> kfn
+cwh OR vvw -> ttb
+qkf AND wsv -> pqc
+rdj OR kfv -> gdb
+x08 AND y08 -> jrr
+x02 AND y02 -> vdf
+x12 XOR y12 -> nft
+ptf OR jrr -> sqm
+tdv OR wjp -> cjw
+qvr AND fnq -> mch
+x28 XOR y28 -> cfj
+gtn XOR qmt -> z06
+mqn OR jpj -> bwg
+x36 XOR y36 -> fbb
+qht OR bfm -> htq
+y42 AND x42 -> mkg
+ksn XOR nft -> jpj
+x20 AND y20 -> pfj
+cmt AND nbq -> gmc
+rbd XOR knm -> z25
+pvj XOR ksp -> z42
+kgj OR stc -> www
+tpf XOR vhb -> z20
+pjd OR dsg -> mwv
+cbs XOR ttb -> z35
+bfk OR jvm -> gwb
+ffj XOR rpg -> z17
+vjr OR kwg -> pkr
+pvj AND ksp -> dkc
+y37 XOR x37 -> cvr
+btv XOR cfj -> z28
+gtq OR qgf -> fmt
+nbq XOR cmt -> z39
+wgq AND dqj -> tws
+x24 AND y24 -> sqt
+whj OR pnn -> bmp
+x02 XOR y02 -> wsv
+stg AND qpp -> dnf
+kbn XOR jvp -> z30
+y39 AND x39 -> gwq
+cds AND rkv -> nph
+kvf XOR gwb -> z18
+mkg OR dkc -> sch
+bqh XOR rjf -> z19
+hck XOR cvr -> z37
+jmk OR ssv -> rkv
+x21 AND y21 -> cgd
+pqc OR vdf -> bkh
+rff OR mts -> rpg
+bkh AND bcj -> rhq
+bnv OR bst -> stg
+bwg XOR mfn -> z13
+sgt AND scc -> bnv
+btv AND cfj -> tdv
+svs AND hgh -> rff
+hbw AND vfm -> kwg
+x40 XOR y40 -> scc
+y17 AND x17 -> jvm
+y34 AND x34 -> chv
+y35 AND x35 -> bbh
+mdv OR rft -> rnq
+fqf AND chv -> cwh
+y28 AND x28 -> wjp
+sch AND srj -> whj
+htr OR rhq -> rjc
+x05 XOR y05 -> dqp
+cvn OR qnk -> cjg
+y14 AND x14 -> tfr
+y11 XOR x11 -> rtk
+jfq AND fbb -> trr
+ppb AND hmr -> hqd
+gtb OR hvv -> gtn
+y44 XOR x44 -> rrq
+rtk XOR htq -> z11
+x01 XOR y01 -> jjd
+hmv XOR rts -> z08
+y10 XOR x10 -> vpc
+jvp AND kbn -> gtq
+cjw AND ntj -> dtj
+x22 AND y22 -> prp
+ppb XOR hmr -> z15
+y18 AND x18 -> jkm
+x39 XOR y39 -> nbq
+jjd AND whb -> wbw
+x34 XOR y34 -> vvw
+x19 AND y19 -> wqs
+gwq OR gmc -> sgt
+rbd AND knm -> rdj
+srj XOR sch -> z43
+y05 AND x05 -> gtb
+x08 XOR y08 -> hmv
+y25 AND x25 -> kfv
+cgd OR jth -> dqj
+vpc XOR vgp -> z10
+tws OR prp -> hbw
+jjm OR fsb -> nbm
+wdw OR vqt -> cmt
+rrq AND bmp -> cbv
+rts AND hmv -> ptf
+svs XOR hgh -> z16
+y41 XOR x41 -> qpp
+ntj XOR cjw -> z29
+ffj AND rpg -> bfk
+gqr OR cbv -> z45
+x25 XOR y25 -> knm
+chc XOR rnq -> z33
+y43 XOR x43 -> srj
+vgp AND vpc -> qht
+x00 XOR y00 -> z00
+cds XOR rkv -> rts
+x24 XOR y24 -> kcv
+x32 AND y32 -> rft
+nbm XOR dqp -> z05
+x35 XOR y35 -> cbs
+mch OR tfr -> ppb
+x16 AND y16 -> mts
+www XOR qdf -> z27
+x23 AND y23 -> vjr
+x26 XOR y26 -> bvp
+gtn AND qmt -> jmk
+x29 XOR y29 -> ntj
+y19 XOR x19 -> bqh
+rjf AND bqh -> cmf
+y38 XOR x38 -> jsg
+x32 XOR y32 -> kkd
+y03 XOR x03 -> bcj
+y31 XOR x31 -> svg
+y22 XOR x22 -> wgq
+qkf XOR wsv -> z02
+bvp XOR gdb -> kgj
+x04 XOR y04 -> cjb
+x17 XOR y17 -> ffj
+y37 AND x37 -> dsg
+y27 AND x27 -> wth
+y23 XOR x23 -> vfm
+sgt XOR scc -> z40
+mmb OR vjh -> fqf
+qcm AND twv -> jth
+y09 XOR x09 -> mtg
+sdj OR nph -> z07
+wgq XOR dqj -> z22
+trr OR kfn -> hck
+y27 XOR x27 -> qdf
+kcv XOR pkr -> z24
+x42 XOR y42 -> pvj
+x40 AND y40 -> bst
+svg AND fmt -> qnk

2024/go/day25/day25.go

@@ -0,0 +1,76 @@
+package day25
+
+import (
+	"fmt"
+	"strings"
+	"math"
+)
+
+type Lock struct {
+	diagram string
+	combination int
+}
+
+type Key struct {
+	diagram string
+	combination int
+}
+
+type Pair struct {
+	l Lock
+	k Key
+}
+
+func Part1(input string) int {
+	data := strings.Split(input, "\n\n")
+	locks := make([]Lock, 0)
+	keys := make([]Key, 0)
+	pairs := make([]Pair, 0)
+
+	for _, in := range data {
+		if in[0] == '#' {
+			locks = append(locks, Lock{diagram: in, combination: combination(in, '.')  })
+		} else {
+			keys = append(keys, Key{diagram: in, combination: combination(in, '#')})
+		}
+	}
+	
+	for _, l := range locks {
+		for _, k := range keys {
+			if key_fits(l.combination, k.combination) {
+				pairs = append(pairs, Pair{l: l, k: k})
+			}
+		}
+	}
+	fmt.Printf("locks: %d, keys: %d\n", len(locks), len(keys))
+	fmt.Printf("pair0 lock\n%s\n%d\n", pairs[0].l.diagram , pairs[0].l.combination)
+	fmt.Printf("pair0 key\n%s\n%d\n",pairs[0].k.diagram, pairs[0].k.combination)
+	return len(pairs)
+}
+
+func Part2(input string) int {
+	return 0
+}
+
+func combination(d string, k rune) int {
+	comb := 0
+	rows := strings.Split(d, "\n")
+	columns := len(rows[0])
+	for _, r := range rows {
+		for i, c := range r {
+			if c == k {
+				comb += 1 * int(math.Pow10(columns - i - 1))
+			}
+		}
+	}
+	return comb
+}
+
+func key_fits(l int, k int) bool {
+	for i:=1;i<6;i++ {
+		ll := l % int(math.Pow10(i))
+		kk := k % int(math.Pow10(i))
+		if ll  < kk { return false }
+	}
+	return true
+}

2024/go/day25/day25_test.go

@@ -0,0 +1,24 @@
+package day25
+
+import (
+	"log"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestPart1(t *testing.T) {
+	data, err := os.ReadFile("input.txt")
+	if err != nil {
+		log.Fatalf("failed to read file: %s", err)
+	}
+
+	r := Part1(string(data))
+	require.Equal(t, 0, r)
+}
+
+func TestPart2(t *testing.T) {
+	r := Part2("")
+	require.Equal(t, 0, r)
+}

2024/go/go.mod

@@ -1,15 +1,14 @@
 module adventofcode2024
 
-go 1.19
+go 1.23.2
+
+toolchain go1.23.5
 
 require (
 	github.com/deckarep/golang-set/v2 v2.7.0
-	github.com/luxedo/esb_fireplace-go v0.3.0
 	golang.org/x/exp v0.0.0-20241009180824-f66d83c29e7c
 )
 
-require github.com/spf13/pflag v1.0.5 // indirect
-
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect

2024/go/go.sum

@@ -2,12 +2,8 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/deckarep/golang-set/v2 v2.7.0 h1:gIloKvD7yH2oip4VLhsv3JyLLFnC0Y2mlusgcvJYW5k=
 github.com/deckarep/golang-set/v2 v2.7.0/go.mod h1:VAky9rY/yGXJOLEDv3OMci+7wtDpOF4IN+y82NBOac4=
-github.com/luxedo/esb_fireplace-go v0.3.0 h1:zhpWG9AJfWEzqiaYsPjlBAwIMa1IF1gWoQoM4zvdLxI=
-github.com/luxedo/esb_fireplace-go v0.3.0/go.mod h1:L8zIvYDHIKTHc3g3VACvjS0qBHvKmt31KRjWLP5ftkU=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
-github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 golang.org/x/exp v0.0.0-20241009180824-f66d83c29e7c h1:7dEasQXItcW1xKJ2+gg5VOiBnqWrJc+rq0DPKyvvdbY=

2024/go/main.go

@@ -26,6 +26,11 @@ import (
 	"adventofcode2024/day17"
 	"adventofcode2024/day18"
 	"adventofcode2024/day19"
+	"adventofcode2024/day21"
+	"adventofcode2024/day22"
+	"adventofcode2024/day23"
+	"adventofcode2024/day24"
+	"adventofcode2024/day25"
 	"adventofcode2024/utils"
 )
 
@@ -90,6 +95,21 @@ func main() {
 	case 19:
 		fmt.Printf("part 1: %d\n", day19.Part1(utils.Readfile(d)))
 		fmt.Printf("part 2: %d\n", day19.Part2(utils.Readfile(d)))
+	case 21:
+		fmt.Printf("part 1: %d\n", day21.Part1(utils.Readfile(d)))
+		fmt.Printf("part 2: %d\n", day21.Part2(utils.Readfile(d)))
+	case 22:
+		fmt.Printf("part 1: %d\n", day22.Part1(utils.Readfile(d)))
+		fmt.Printf("part 2: %d\n", day22.Part2(utils.Readfile(d)))
+	case 23:
+		fmt.Printf("part 1: %d\n", day23.Part1(utils.Readfile(d)))
+		fmt.Printf("part 2: %d\n", day23.Part2(utils.Readfile(d)))
+	case 24:
+		fmt.Printf("part 1: %d\n", day24.Part1(utils.Readfile(d)))
+		fmt.Printf("part 2: %d\n", day24.Part2(utils.Readfile(d)))
+	case 25:
+		fmt.Printf("part 1: %d\n", day25.Part1(utils.Readfile(d)))
+		fmt.Printf("part 2: %d\n", day25.Part2(utils.Readfile(d)))
 	default:
 		panic(fmt.Errorf("no such day: %d", d))
 	}
@@ -99,7 +119,7 @@ func main() {
 
 // Reads day from os.Args.
 func day() int {
-	latest := 19
+	latest := 24
 	if len(os.Args) == 1 {
 		return latest
 	}

2024/go/utils/dijkstra/graph.go

@@ -1,7 +1,6 @@
 package dijkstra
 
 import (
-	"fmt"
 	"math"
 	"sync"
 )
@@ -92,7 +91,7 @@ func getShortestPath(startNode *Node, endNode *Node, g *ItemGraph) ([]Point, int
 		pathval = prev[pathval]
 	}
 	finalArr = append(finalArr, pathval)
-	fmt.Println(finalArr)
+	//	fmt.Println(finalArr)
 	for i, j := 0, len(finalArr)-1; i < j; i, j = i+1, j-1 {
 		finalArr[i], finalArr[j] = finalArr[j], finalArr[i]
 	}

2024/go/utils/memo/memo.go

@@ -0,0 +1,47 @@
+package memo
+
+import "sync"
+
+type Func func(key interface{}) interface{}
+
+type result struct {
+	value interface{}
+}
+
+type Memo struct {
+	f     Func
+	cache map[interface{}]result
+	mu    sync.RWMutex // Allows concurrent reads.
+}
+
+func New(f Func) *Memo {
+	return &Memo{
+		f:     f,
+		cache: make(map[interface{}]result),
+	}
+}
+
+func (memo *Memo) Get(key interface{}) interface{} {
+	// First, try to read the cache using a read lock.
+	memo.mu.RLock()
+	res, ok := memo.cache[key]
+	memo.mu.RUnlock()
+	if ok {
+		return res.value
+	}
+
+	// Compute the result without holding the lock.
+	computed := memo.f(key)
+
+	// Now acquire a write lock to update the cache.
+	memo.mu.Lock()
+	// Double-check: another goroutine may have stored the result in the meantime.
+	res, ok = memo.cache[key]
+	if !ok {
+		res.value = computed
+		memo.cache[key] = res
+	}
+	memo.mu.Unlock()
+
+	return res.value
+}

2024/go/utils/ringbuffer/ringbuffer.go

@@ -0,0 +1,56 @@
+package ringbuffer
+
+import (
+	"sync"
+)
+
+type RingBuffer[T any] struct {
+	buffer []T
+	size   int
+	mu     sync.Mutex
+	write  int
+	count  int
+}
+
+// NewRingBuffer creates a new ring buffer with a fixed size.
+func NewRingBuffer[T any](size int) *RingBuffer[T] {
+	return &RingBuffer[T]{
+		buffer: make([]T, size),
+		size:   size,
+	}
+}
+
+// Add inserts a new element into the buffer, overwriting the oldest if full.
+func (rb *RingBuffer[T]) Add(value T) {
+	rb.mu.Lock()
+	defer rb.mu.Unlock()
+
+	rb.buffer[rb.write] = value
+	rb.write = (rb.write + 1) % rb.size
+
+	if rb.count < rb.size {
+		rb.count++
+	}
+}
+
+// Get returns the contents of the buffer in FIFO order.
+func (rb *RingBuffer[T]) Get() []T {
+	rb.mu.Lock()
+	defer rb.mu.Unlock()
+
+	result := make([]T, 0, rb.count)
+
+	for i := 0; i < rb.count; i++ {
+		index := (rb.write + rb.size - rb.count + i) % rb.size
+		result = append(result, rb.buffer[index])
+	}
+
+	return result
+}
+
+// Len returns the current number of elements in the buffer.
+func (rb *RingBuffer[T]) Len() int {
+	rb.mu.Lock()
+	defer rb.mu.Unlock()
+	return rb.count
+}