https://adventofcode.com/2020/day/6

customs_declaration_forms.go

package main

import (
	"io/ioutil"
	"strings"
)

func main() {
	bytes, _ := ioutil.ReadFile("./input.txt")
	input := strings.TrimRight(string(bytes), "\n")

	sum := 0

	for _, group := range strings.Split(input, "\n\n") {
		m := make(map[rune]bool)
		for _, row := range strings.Fields(group) {
			for _, c := range row {
				m[c] = true
			}
		}
		sum += len(m)
	}

	println(sum)
}

customs_declaration_forms2.go

package main

import (
	"io/ioutil"
	"strings"
)

func main() {
	bytes, _ := ioutil.ReadFile("./input.txt")
	input := strings.TrimRight(string(bytes), "\n")

	sum := 0

	for _, group := range strings.Split(input, "\n\n") {
		m := make(map[rune]int)
		groupCount := 0
		for _, row := range strings.Fields(group) {
			for _, c := range row {
				if val, ok := m[c]; ok {
					m[c] = val + 1
				} else {
					m[c] = 1
				}
			}
			groupCount++
		}

		for _, element := range m {
			if element == groupCount {
				sum++
			}
		}
	}

	println(sum)
}