aoc2024/day-11/internal/one/util.go

package one

import (
	"bufio"
	"io"
	"math"
	"strconv"
	"strings"
)

func parseLines(r io.Reader) ([]int, error) {
	var numbers []int

	scanner := bufio.NewScanner(r)
	for scanner.Scan() {
		numbers = numbersFromString(scanner.Text())
	}

	if err := scanner.Err(); err != nil {
		return nil, err
	}

	return numbers, nil
}

func numbersFromString(s string) []int {
	splitted := strings.Fields(s)

	var nums []int
	for _, part := range splitted {
		nums = append(nums, mustConv(part))
	}
	return nums
}

func mustConv(s string) int {
	n, err := strconv.Atoi(s)
	if err != nil {
		panic(err)
	}
	return n
}

func splitNumber(n int) (int, int) {
	factor := int(math.Pow10(lenItoa(n) / 2))

	right := n % factor
	left := int(n / factor)

	return left, right
}

func lenItoa(n int) int {
	return len(strconv.Itoa(n))
}