2019/day5/main.go

package main

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

func main() {
	file, err := os.Open("input.txt")
	if err != nil {
		log.Fatal(err)
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	if !scanner.Scan() {
		log.Fatalln("Problem while read line.")
		return
	}

	stringarr := strings.Split(scanner.Text(), ",")
	var t2 = []int{}

	for _, i := range stringarr {
		j, err := strconv.Atoi(i)
		if err != nil {
			panic(err)
		}
		t2 = append(t2, j)
	}
	wip := make([]int, len(t2))
	// ========= Finish now, we can solve the task ======
	copy(wip, t2)
	err = ParseArray(wip)
	if err != nil {
		log.Println(err)
	}
}

func ParseArray(list []int) error {
	for i := 0; i < len(list); i += 4 {
		//log.Println(strconv.Itoa(i) +  " -> "  + strconv.Itoa(list[i]))
		cmd := list[i]

		if cmd == 99 {
			return nil
		}
		sum := 0

		mode1 := 0
		mode2 := 0
		//mode3 := 0

		count := CountDigits(cmd)
		if count > 2 {
			cmdStr := strconv.Itoa(cmd)
			cmd, _ = strconv.Atoi(cmdStr[len(cmdStr)-2:])

			if count >= 3 {
				mode1, _ = strconv.Atoi(cmdStr[len(cmdStr)-3 : len(cmdStr)-2])
			}
			if count >= 4 {
				mode2, _ = strconv.Atoi(cmdStr[len(cmdStr)-4 : len(cmdStr)-3])
			}
			if count >= 5 {
				//mode3, _ = strconv.Atoi(cmdStr[len(cmdStr)-4:len(cmdStr)-3])
			}
		}

		if cmd == 1 {
			num1 := -1
			num2 := -1
			if mode1 == 1 {
				num1 = list[i+1]
			} else {
				num1 = list[list[i+1]]
			}
			if mode2 == 1 {
				num2 = list[i+2]
			} else {
				num2 = list[list[i+2]]
			}
			sum = num1 + num2
			list[list[i+3]] = sum

		} else if cmd == 2 {

			num1 := -1
			num2 := -1
			if mode1 == 1 {
				num1 = list[i+1]
			} else {
				num1 = list[list[i+1]]
			}
			if mode2 == 1 {
				num2 = list[i+2]
			} else {
				num2 = list[list[i+2]]
			}
			sum = num1 * num2
			list[list[i+3]] = sum
		} else if cmd == 3 {
			var input int
			fmt.Scanf("%d", &input)
			list[list[i+1]] = input
			i = i - 2
		} else if cmd == 4 {
			if mode1 == 1 {
				fmt.Print(list[i+1])
			} else {
				fmt.Print(list[list[i+1]])
			}
			i = i - 2
		} else if cmd == 5 {
			num1 := -1
			if mode1 == 1 {
				num1 = list[i+1]
			} else {
				num1 = list[list[i+1]]
			}
			num2 := -1
			if mode2 == 1 {
				num2 = list[i+2]
			} else {
				num2 = list[list[i+2]]
			}
			if num1 != 0 {
				i = num2 - 4
			} else {
				i -= 1
			}
		} else if cmd == 6 {
			num1 := -1
			if mode1 == 1 {
				num1 = list[i+1]
			} else {
				num1 = list[list[i+1]]
			}
			num2 := -1
			if mode2 == 1 {
				num2 = list[i+2]
			} else {
				num2 = list[list[i+2]]
			}
			if num1 == 0 {
				i = num2 - 4
			} else {
				i -= 1
			}
		} else if cmd == 7 {
			num1 := -1
			if mode1 == 1 {
				num1 = list[i+1]
			} else {
				num1 = list[list[i+1]]
			}
			num2 := -1
			if mode2 == 1 {
				num2 = list[i+2]
			} else {
				num2 = list[list[i+2]]
			}
			if num1 < num2 {
				list[list[i+3]] = 1
			} else {
				list[list[i+3]] = 0
			}
		} else if cmd == 8 {
			num1 := -1
			if mode1 == 1 {
				num1 = list[i+1]
			} else {
				num1 = list[list[i+1]]
			}
			num2 := -1
			if mode2 == 1 {
				num2 = list[i+2]
			} else {
				num2 = list[list[i+2]]
			}
			if num1 == num2 {
				list[list[i+3]] = 1
			} else {
				list[list[i+3]] = 0
			}
		} else {
			return errors.New("Wrong Command (" + strconv.Itoa(list[i]) + ") at position " + strconv.Itoa(i))
		}
	}
	return nil
}

func CountDigits(i int) int {
	count := 0
	for i != 0 {
		i /= 10
		count = count + 1
	}
	return count
}