adventofcode/2018/day02/day02.go

package main

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

func main() {
	inp := StdinToStringSlice()
	part1(inp)
	part2(inp)
}

func part1(inp []string) {
	var twos, threes int
	for _, v := range inp {
		var vintwos, vinthrees bool
		for i := range v {
			if !vintwos && strings.Count(v, string(v[i])) == 2 {
				twos++
				vintwos = true
			}
			if !vinthrees && strings.Count(v, string(v[i])) == 3 {
				threes++
				vinthrees = true
			}
		}
	}
	fmt.Println(twos * threes)
}

func part2(inp []string) {
	for _, v1 := range inp {
		for _, v2 := range inp {
			if v1 == v2 {
				continue
			}
			var diff, diffIdx int
			for k := range v1 {
				if v1[k] != v2[k] {
					diff++
					diffIdx = k
				}
				if diff > 1 {
					continue
				}
			}
			if diff == 1 {
				fmt.Println(v1[:diffIdx] + v1[diffIdx+1:])
				return
			}
		}
	}
}

func StdinToStringSlice() []string {
	var input []string
	scanner := bufio.NewScanner(os.Stdin)
	for scanner.Scan() {
		input = append(input, scanner.Text())
	}
	return input
}

func Atoi(i string) int {
	var ret int
	var err error
	if ret, err = strconv.Atoi(i); err != nil {
		log.Fatal("Invalid Atoi")
	}
	return ret
}