2024 Day 24 complete

Part 2 solved manually, working on a programmatic solution

2024/day24/main.go

@@ -0,0 +1,192 @@
+package main
+
+import (
+	"fmt"
+	"sort"
+	"strconv"
+	"strings"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	inp := h.StdinToStringSlice()
+	part1(inp)
+	fmt.Println()
+	part2(inp)
+}
+
+func part1(inp []string) {
+	fmt.Println("# Part 1")
+	dev, gates := parseInput1(inp)
+	// Perform all logic
+	gateDone := make(map[int]bool)
+	for len(gateDone) != len(gates)-1 {
+		for i := range gates {
+			if _, ok := gateDone[i]; !ok {
+				pts := strings.Split(gates[i], " ")
+				var w1, w2, ok bool
+				if w1, ok = dev[pts[0]]; ok {
+					if w2, ok = dev[pts[2]]; ok {
+						switch pts[1] {
+						case "AND":
+							dev[pts[4]] = w1 && w2
+						case "OR":
+							dev[pts[4]] = w1 || w2
+						case "XOR":
+							dev[pts[4]] = w1 != w2
+						}
+						gateDone[i] = true
+					}
+				}
+			}
+		}
+	}
+	fmt.Println(findValueOf(dev, "z"))
+}
+
+// Not fully working yet... I solved this part manually.
+func part2(inp []string) {
+	fmt.Println("# Part 2")
+	gates := parseInput2(inp)[1]
+
+	var swapped []string
+	var c0 string
+
+	for i := 0; i < 45; i++ {
+		n := fmt.Sprintf("%02d", i)
+		var m1, n1, r1, z1, c1 string
+
+		m1 = find("x"+n, "y"+n, "XOR", gates)
+		n1 = find("x"+n, "y"+n, "AND", gates)
+
+		if c0 != "" {
+			r1 = find(c0, m1, "AND", gates)
+			if r1 == "" {
+				m1, n1 = n1, m1
+				swapped = append(swapped, m1, n1)
+				r1 = find(c0, m1, "AND", gates)
+			}
+
+			z1 = find(c0, m1, "XOR", gates)
+
+			if strings.HasPrefix(m1, "z") {
+				m1, z1 = z1, m1
+				swapped = append(swapped, m1, z1)
+			}
+
+			if strings.HasPrefix(n1, "z") {
+				n1, z1 = z1, n1
+				swapped = append(swapped, n1, z1)
+			}
+
+			if strings.HasPrefix(r1, "z") {
+				r1, z1 = z1, r1
+				swapped = append(swapped, r1, z1)
+			}
+
+			c1 = find(r1, n1, "OR", gates)
+		}
+
+		if strings.HasPrefix(c1, "z") && c1 != "z45" {
+			c1, z1 = z1, c1
+			swapped = append(swapped, c1, z1)
+		}
+
+		if c0 == "" {
+			c0 = n1
+		} else {
+			c0 = c1
+		}
+	}
+
+	// Sort and join swapped wires
+	sort.Strings(swapped)
+	fmt.Println(strings.Join(swapped, ","))
+}
+
+func parseInput1(inp []string) (map[string]bool, []string) {
+	dev := make(map[string]bool)
+	var gates []string
+	var inGates bool
+	for i := range inp {
+		if len(inp[i]) == 0 {
+			inGates = true
+		}
+		if !inGates {
+			if inp[i][3] == ':' {
+				wire := inp[i][:3]
+				v := inp[i][5] == '1'
+				dev[wire] = v
+			}
+		} else {
+			gates = append(gates, inp[i])
+		}
+	}
+	return dev, gates
+}
+
+func parseInput2(inp []string) [][]string {
+	var parts [][]string
+	var currPt []string
+	for _, line := range inp {
+		if line == "" {
+			if len(currPt) > 0 {
+				parts = append(parts, currPt)
+				currPt = []string{}
+			}
+		} else {
+			currPt = append(currPt, line)
+		}
+	}
+	if len(currPt) > 0 {
+		parts = append(parts, currPt)
+	}
+	return parts
+}
+
+func findHighestReg(dev map[string]bool) int {
+	var highest string
+	for i := range dev {
+		if i > highest {
+			highest = i
+		}
+	}
+	ret, _ := strconv.Atoi(highest[1:])
+	return ret
+}
+
+func findValueOf(dev map[string]bool, register string) int64 {
+	var highest string
+	for i := range dev {
+		if i > highest {
+			highest = i
+		}
+	}
+	get, _ := strconv.Atoi(highest[1:])
+	var val int64
+	for i := get; ; i-- {
+		key := fmt.Sprintf("%s%02d", register, i)
+		v, ok := dev[key]
+		if !ok {
+			break
+		} else {
+			val = val << 1
+			if v {
+				val += 1
+			}
+		}
+	}
+	return val
+}
+
+func find(w1, w2, op string, gates []string) string {
+	for _, gate := range gates {
+		if strings.HasPrefix(gate, fmt.Sprintf("%s %s %s", w1, op, w2)) ||
+			strings.HasPrefix(gate, fmt.Sprintf("%s %s %s", w2, op, w2)) {
+			parts := strings.Split(gate, " -> ")
+			return parts[len(parts)-1]
+		}
+	}
+	return ""
+}