aoc-2024/cmd/day_1/main.go

package main

import (
	"errors"
	"fmt"
	"io"
	"log"
	"slices"
	"strconv"
)

const (
	MAX_LOOP = 1_000_000
)

var MAX_INT int = int(^uint(0) >> 1)
var INT_SZ int = 1

func main() {
	tmp := MAX_INT
	for tmp > 0 {
		INT_SZ++
		tmp >>= 1
	}
	left := make([]int, 0, 1024)
	right := make([]int, 0, 1024)

	var lStr, rStr string
	for i := 0; i < MAX_LOOP; i++ {
		n, err := fmt.Scan(&lStr, &rStr)
		if errors.Is(err, io.EOF) {
			break
		}
		if err != nil {
			log.Fatal("Unexpected error while reading input: ", err)
		}
		if n != 2 {
			log.Fatal(fmt.Sprintf("Unexpected number of fields at line %d of input", i+1))
		}
		l, err := strconv.ParseInt(lStr, 10, INT_SZ)
		r, err := strconv.ParseInt(rStr, 10, INT_SZ)
		left = append(left, int(l))
		right = append(right, int(r))
	}

	fmt.Printf("distance = %d\n", distance(left, right))
}

func distance(left, right []int) int {
	slices.Sort(left)
	slices.Sort(right)

	var sum int
	for i := 0; i < len(left); i++ {
		subSum := left[i] - right[i]
		if subSum < 0 {
			subSum *= -1
		}
		sum += subSum
	}
	return sum
}