feat(angch/2025-07): Initial

Author: angch

angch/2025-07/main.go

@@ -0,0 +1,73 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+	"time"
+)
+
+func day7(file string) (part1, part2 int) {
+	f, err := os.Open(file)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer f.Close()
+	scanner := bufio.NewScanner(f)
+
+	scanner.Scan()
+	t := scanner.Bytes()
+	beams := map[int]int{}
+	for x, c := range t {
+		if c == 'S' {
+			beams[x] = 1
+		}
+	}
+
+	part2 = 1
+	for scanner.Scan() {
+		t := scanner.Bytes()
+		rest := 0
+		for x, c := range t {
+			if c == '^' && beams[x] > 0 {
+				split := 0
+				if x > 0 {
+					beams[x-1] += beams[x]
+					split += beams[x]
+				}
+				if x < len(t) {
+					beams[x+1] += beams[x]
+					split += beams[x]
+				}
+				delete(beams, x)
+				rest++
+				part1++
+			}
+		}
+		if rest == 0 {
+			sum := 0
+			for _, i := range beams {
+				sum += i
+			}
+			// fmt.Println(beams, len(beams), sum)
+			part2 = sum
+		}
+	}
+
+	return
+}
+
+func main() {
+	log.SetFlags(log.Lshortfile | log.LstdFlags)
+	t1 := time.Now()
+	part1, part2 := day7("test.txt")
+	fmt.Println(part1, part2)
+	if part1 != 21 || part2 != 40 {
+		log.Fatal("Test failed ", part1, part2)
+	}
+
+	part1, part2 = day7("input.txt")
+	fmt.Println(part1, part2)
+	fmt.Println("Elapsed time:", time.Since(t1))
+}

angch/2025-07/test.txt

@@ -0,0 +1,16 @@
+.......S.......
+...............
+.......^.......
+...............
+......^.^......
+...............
+.....^.^.^.....
+...............
+....^.^...^....
+...............
+...^.^...^.^...
+...............
+..^...^.....^..
+...............
+.^.^.^.^.^...^.
+...............