day01_calories.go

package main

// have to install ioutil
// go get io/ioutil

import (
	"fmt"
	"io/ioutil"
	"log"
	"sort"
	"strconv"
	"strings"
)

func readElfCalorieFile(filePath string) [][]int {
	body, err := ioutil.ReadFile(filePath)

	if err != nil {
		log.Fatalf("unable to read file: %v", err)
	}

	allElfCalories := make([][]int, 0)

	// run through each elf seprately
	caloriesString := strings.Split(strings.Trim(string(body), "\n"), "\n\n")
	for _, elfCaloriesString := range caloriesString {
		elfCalories := make([]int, 0)

		itemCalories := strings.Split(elfCaloriesString, "\n")
		for _, itemCalorie := range itemCalories {
			i, _ := strconv.Atoi(itemCalorie)
			elfCalories = append(elfCalories, i)
		}

		allElfCalories = append(allElfCalories, elfCalories)
	}

	return allElfCalories
}

func sumElfCalories(caloriesByElf [][]int) []int {
	// return sorted array
	summedCalories := make([]int, 0)

	for _, elfCalories := range caloriesByElf {
		var currElfTotal = 0
		for _, itemCalorie := range elfCalories {
			currElfTotal += itemCalorie
		}

		summedCalories = append(summedCalories, currElfTotal)
	}

	sort.Ints(summedCalories)
	return summedCalories
}

func day01() {
	var caloriesByElf = readElfCalorieFile("2022/data/day01_sample.txt")
	result := sumElfCalories(caloriesByElf)

	if result[len(result)-1] != 24000 {
		panic("Part 1 example is failing")
	}

	caloriesByElf = readElfCalorieFile("2022/data/day01_input.txt")
	result = sumElfCalories(caloriesByElf)
	fmt.Println("Part 1:", result[len(result)-1])

	fmt.Println("Part 2:", result[len(result)-1]+result[len(result)-2]+result[len(result)-3])
}