package main

import (
	"bufio"
	"fmt"
	"log"
	"os"
	"sort"
	"strconv"
	"strings"
)

func optimized() {
	fmt.Println("Optimized Code by ChatGPT")

	// Open the input file
	file, err := os.Open("./input.txt")
	if err != nil {
		log.Fatalf("Error opening input.txt: %v", err)
	}
	defer file.Close()

	var (
		listA, listB []int
	)

	// Read and parse input file
	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := strings.Fields(scanner.Text())
		if len(line) != 2 {
			log.Fatalf("Invalid input format: %s", scanner.Text())
		}
		num1, err1 := strconv.Atoi(line[0])
		num2, err2 := strconv.Atoi(line[1])
		if err1 != nil || err2 != nil {
			log.Fatalf("Error converting input to integers: %v, %v", err1, err2)
		}
		listA = append(listA, num1)
		listB = append(listB, num2)
	}

	if err := scanner.Err(); err != nil {
		log.Fatalf("Error reading file: %v", err)
	}

	// Part 1: Calculate sum of absolute differences
	sort.Ints(listA)
	sort.Ints(listB)

	sumPart1 := 0
	for i := 0; i < len(listA); i++ {
		diff := listA[i] - listB[i]
		if diff < 0 {
			diff = -diff
		}
		sumPart1 += diff
	}
	fmt.Printf("Sum of Part 1: %d\n", sumPart1)

	// Part 2: Calculate weighted sum of matches
	sumPart2 := 0
	countMap := make(map[int]int)

	// Populate a map for quick lookup
	for _, num := range listB {
		countMap[num]++
	}

	for _, num := range listA {
		if count, found := countMap[num]; found {
			sumPart2 += count * num
		}
	}

	fmt.Printf("Sum of Part 2: %d\n", sumPart2)
}