Advent of code day4

package main

import (
	"fmt"
	"strconv"
	"strings"
)

func conv_to_intslice(puzzle_input string) []int {
	// Split into slice
	str_code_range := strings.Split(puzzle_input, "-")
	// convert to ints
	code_range := []int{}
	for _, i := range str_code_range {
		j, err := strconv.Atoi(i)
		if err != nil {
			panic(err)
		}
		code_range = append(code_range, j)
	}
	return code_range
}

func check_rules(code int) bool {
	// convert to string
	val_str := strconv.Itoa(code)
	adjacent_count := 1
	rule_adjacent := false
	var last int

	for pos, digit_char := range val_str {
		digit, _ := strconv.Atoi(string(digit_char))

		// Set first
		if pos == 0 {
			last = digit
			continue
		}

		if digit < last {
			return false
		} else if digit == last {
			adjacent_count++
		} else {
			if adjacent_count == 2 {
				rule_adjacent = true
			} else {
				adjacent_count = 1
			}
		}

		last = digit
	}

	if rule_adjacent || adjacent_count == 2 {
		return true
	} else {
		return false
	}
}

func filter_code(puzzle_input string) {
	possible_matches := 0
	code_range := conv_to_intslice(puzzle_input)
	for code := code_range[0]; code < code_range[1]; code++ {
		if check_rules(code) {
			possible_matches++
		}
	}
	fmt.Println(possible_matches)
}

func main() {
	var puzzle_input = "178416-676461"
	filter_code(puzzle_input)
}