Solution for 2024, day 25

Author: lucianoq

2024/25/Makefile

@@ -0,0 +1,13 @@
+input:
+	http "https://adventofcode.com/2024/day/25/input" "Cookie:session=${AOC_SESSION};" >input
+
+main1:
+	go build -o main1 main1.go
+
+.PHONY: run1 clean
+
+run1: main1 input
+	./main1 <input
+
+clean:
+	rm -f main1 input

2024/25/main1.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+)
+
+const (
+	Pins   = 5
+	Height = 7
+)
+
+type Schematic [Pins]int
+
+func main() {
+	keys, locks := parseInput()
+
+	count := 0
+	for _, key := range keys {
+		for _, lock := range locks {
+			if !overlap(key, lock) {
+				count++
+			}
+		}
+	}
+	fmt.Println(count)
+}
+
+func overlap(key, lock Schematic) bool {
+	for i := 0; i < Pins; i++ {
+		if key[i]+lock[i] > Height-2 {
+			return true
+		}
+	}
+	return false
+}
+
+func parseInput() ([]Schematic, []Schematic) {
+	var keys, locks []Schematic
+
+	scanner := bufio.NewScanner(os.Stdin)
+	for {
+		m := [Height]string{}
+		for i := 0; i < Height; i++ {
+			if !scanner.Scan() {
+				return keys, locks
+			}
+			m[i] = scanner.Text()
+		}
+
+		val, isLock := parseSchema(m)
+		if isLock {
+			locks = append(locks, val)
+		} else {
+			keys = append(keys, val)
+		}
+		scanner.Scan()
+	}
+}
+
+func parseSchema(m [Height]string) (Schematic, bool) {
+	res := Schematic{}
+	for j := 0; j < Pins; j++ {
+		count := 0
+		// ignore first and last line
+		for i := 1; i < Height-1; i++ {
+			if m[i][j] == '#' {
+				count++
+			}
+		}
+		res[j] = count
+	}
+	return res, m[0] == "#####" && m[Height-1] == "....."
+}