aoc21/04/main.go

package main

import (
	"log"
	"os"
	"strconv"
	"strings"

	"github.com/thoas/go-funk"
)

func main() {
	inputBytes, _ := os.ReadFile("input.txt")
	inputs := strings.Split(string(inputBytes), "\n")

	log.Println("Puzzle 1:", puzzle1(inputs))
	log.Println("Puzzle 2:", puzzle2(inputs))
}

func puzzle1(input []string) int {
	called, bingos := parseBingos(input)
	// Iterate through called numbers
	lastCalledNumber := -1
	firstBingo := -1
callnumbers:
	for _, calledNumber := range called {
		lastCalledNumber = calledNumber
		// Replace called number in every bingo with -1
		for _, bingo := range bingos {
			for i := 0; i < 5; i++ {
				for j := 0; j < 5; j++ {
					if bingo[i][j] == calledNumber {
						bingo[i][j] = -1
					}
				}
			}
		}
		// Check if any bingo has row or column with sum of just 0
		for b, bingo := range bingos {
			// Check rows
			for i := 0; i < 5; i++ {
				if funk.SumInt(bingo[i]) == -5 {
					firstBingo = b
					break callnumbers
				}
			}
			// Check columns
			for i := 0; i < 5; i++ {
				if bingo[0][i]+bingo[1][i]+bingo[2][i]+bingo[3][i]+bingo[4][i] == -5 {
					firstBingo = b
					break callnumbers
				}
			}
		}
	}
	// Get sum of remaining numbers in first bingo
	sum := 0
	for _, row := range bingos[firstBingo] {
		for _, number := range row {
			if number != -1 {
				sum += number
			}
		}
	}
	// Return product of sum and last called number
	return sum * lastCalledNumber
}

func puzzle2(input []string) int {
	called, bingos := parseBingos(input)
	// Iterate through called numbers
	lastCalledNumber := -1
	solvedBingos := []int{}
	lastSolvedBingo := -1
callnumbers:
	for _, calledNumber := range called {
		lastCalledNumber = calledNumber
		// Replace called number in every bingo with -1
		for _, bingo := range bingos {
			for i := 0; i < 5; i++ {
				for j := 0; j < 5; j++ {
					if bingo[i][j] == calledNumber {
						bingo[i][j] = -1
					}
				}
			}
		}
		// Check if any bingo has row or column with sum of just 0
	bingoiter:
		for b, bingo := range bingos {
			// Skip solved bingos
			if funk.ContainsInt(solvedBingos, b) {
				continue bingoiter
			}
			// Check rows
			for i := 0; i < 5; i++ {
				if funk.SumInt(bingo[i]) == -5 {
					// Add bingo to solved bingos
					solvedBingos = append(solvedBingos, b)
					lastSolvedBingo = b
					continue bingoiter
				}
			}
			// Check columns
			for i := 0; i < 5; i++ {
				if bingo[0][i]+bingo[1][i]+bingo[2][i]+bingo[3][i]+bingo[4][i] == -5 {
					// Add bingo to solved bingos
					solvedBingos = append(solvedBingos, b)
					lastSolvedBingo = b
					continue bingoiter
				}
			}
		}
		// Check if all bingos but are solved
		if len(bingos) == len(solvedBingos) {
			break callnumbers
		}
	}
	// Get sum of remaining numbers in last solved bingo
	sum := 0
	for _, row := range bingos[lastSolvedBingo] {
		for _, number := range row {
			if number != -1 {
				sum += number
			}
		}
	}
	// Return product of sum and last called number
	return sum * lastCalledNumber
}

func parseBingos(input []string) (called []int, bingos [][][]int) {
	// Parse called numbers
	called = []int{}
	for _, number := range strings.Split(input[0], ",") {
		no, _ := strconv.Atoi(number)
		called = append(called, no)
	}
	// Parse bingos
	bingos = [][][]int{}
	bingoCurrentRow := 0
	currentBingo := [][]int{}
	for _, line := range input[2:] {
		// Trim spaces
		line = strings.TrimSpace(line)
		// Replace double spaces with single spaces
		line = strings.ReplaceAll(line, "  ", " ")
		// Check if line is empty
		if line == "" {
			continue
		}
		// Parse row
		row := []int{}
		for i, number := range strings.Split(line, " ") {
			if i > 4 {
				break
			}
			no, _ := strconv.Atoi(number)
			row = append(row, no)
		}
		// Add row to bingo
		currentBingo = append(currentBingo, row)
		// Check if bingo is complete
		if bingoCurrentRow == 4 {
			bingos = append(bingos, currentBingo)
			bingoCurrentRow = 0
			currentBingo = [][]int{}
		} else {
			bingoCurrentRow++
		}
	}
	// Return called numbers and bingos
	return
}