advent_of_code_2025/7/solve_2.go

package main

import (
	"bufio"
	"fmt"
	"os"
)

type coord struct {
	x,y int
}

func main() {
	fmt.Println("Advent of Code - Day 7 - Part 2")
	f,_ := os.Open("7/input")
	defer f.Close()
	scanner := bufio.NewScanner(f)
	y := 0
	scanner.Scan()
	y_limit := len(scanner.Text())
	for i := range(scanner.Text()){
		if scanner.Text()[i] == 'S'{
			y = i
		}
	}
	initial_position := coord{0,y}
	x:=1
	var splitters []coord
	for scanner.Scan(){
		line := scanner.Text()
		for i:= range line{
			if line[i] == '^'{
				splitters = append(splitters, coord{x,i})
			}
		}
		x++
	}
	
	limit := coord{x,y_limit}
	res := 0
	store_split := make(map[coord]int)
	res = count_timelines(initial_position, splitters, limit, &store_split)
	fmt.Println(res)
}

func count_timelines(pos coord, splitters []coord, limit coord, store_split* map[coord]int) int {

	ss, ok := (*store_split)[pos]
	if ok {
		return ss
	}
	
	if pos.x >= limit.x || pos.y >= limit.y || pos.y < 0 {
		return 1
	}

	for _,s := range splitters {
		if pos.x == s.x && pos.y == s.y {
			n_pos1:=coord{pos.x, pos.y-1}
			n_pos2:=coord{pos.x, pos.y+1}
			(*store_split)[n_pos1] = count_timelines(coord{pos.x,pos.y-1},splitters, limit, store_split)
			(*store_split)[n_pos2] = count_timelines(coord{pos.x,pos.y+1},splitters, limit, store_split)
			return (*store_split)[n_pos1] + (*store_split)[n_pos2] 
		}
	}

	n_pos := coord{pos.x+1,pos.y}
	(*store_split)[n_pos] = count_timelines(coord{pos.x+1,pos.y},splitters, limit, store_split)
	return (*store_split)[n_pos]

	
}