package main

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

func findValue(sl *[]string, ox bool) {
	var c byte
	if ox {
		c = '1'
	} else {
		c = '0'
	}
	if sl != nil && len(*sl) > 0 {
		size := len((*sl)[0])

		for i := 0; i < size && len(*sl) != 1; i++ {
			var z = make([]string, 0)
			// Check common bit //
			count := 0

			for _, s := range *sl {
				if s[i] == c {
					count++
				}
			}
			var flag bool
			if ox {
				flag = 2*count >= len(*sl)
			} else {
				flag = 2*count > len(*sl)
			}

			// Save with bit criteria //
			for _, s := range *sl {
				if flag && s[i] == '1' || !flag && s[i] == '0' {
					z = append(z, s)
				}
			}

			*sl = z
		}
	}
}

func main() {
	fin, _ := os.Open("input.txt")
	defer fin.Close()

	scan := bufio.NewScanner(fin)
	file := make([]string, 0)
	count := 0
	var counters []int
	var gamma []byte
	var epsilon []byte

	var size int
	for scan.Scan() {
		str := scan.Text()
		file = append(file, str)

		if count == 0 {
			size = len(str)
			counters = make([]int, size)
			gamma = make([]byte, size)
			epsilon = make([]byte, size)
		}

		for i := 0; i < size; i++ {
			if str[i] == '1' {
				counters[i]++
			}
		}

		count++
	}

	// Calc gamma & epsilon

	for i := 0; i < size; i++ {
		if counters[i] > count/2 {
			gamma[i] = '1'
			epsilon[i] = '0'
		} else {
			gamma[i] = '0'
			epsilon[i] = '1'
		}
	}

	g := string(gamma[:])
	e := string(epsilon[:])

	gi, _ := strconv.ParseUint(g, 2, size)
	ei, _ := strconv.ParseUint(e, 2, size)

	fmt.Printf("gamma * epsilon = %d\n", gi*ei)

	/////////////////////////////////////////////////////////////////////////////
	// Second Part //////////////////////////////////////////////////////////////
	var slOx []string = make([]string, len(file))
	var slCO2 []string = make([]string, len(file))

	copy(slOx, file)
	copy(slCO2, file)

	findValue(&slOx, true)
	findValue(&slCO2, false)

	// Print values
	sNum := slOx[0]
	oxRate, _ := strconv.ParseUint(sNum, 2, size)
	fmt.Printf("Oxygen generator rating = %d\n", oxRate)

	sNum = slCO2[0]
	co2Rate, _ := strconv.ParseUint(sNum, 2, size)
	fmt.Printf("CO2 scrubber rating = %d\n", co2Rate)

	fmt.Printf("Life support rating = %d\n", oxRate*co2Rate)
}