AdventOfCode2k16/d08/d08.go

package main

import "strconv"
import "strings"
import "bufio"
import "fmt"
import "os"

type Screen struct {
    Pixels [6][50]bool
}

func NewScreen() Screen {
    var this Screen
    return this
}

func (this *Screen) CreateRect(x int, y int) {
    for i := 0; i < y; i++ {
        for j := 0; j < x; j++ {
            this.Pixels[i][j] = true
        }
    }
}

func (this *Screen) RotateRowByOne(rowIndex int) {
    tmp := this.Pixels[rowIndex][49]
    for i := 49; i > 0; i-- {
        this.Pixels[rowIndex][i] = this.Pixels[rowIndex][i -1]
    }
    this.Pixels[rowIndex][0] = tmp
}

func (this *Screen) RotateRows(rowIndex int, shift int) {
    for ; shift > 0; shift -- {
        this.RotateRowByOne(rowIndex)
    }
}

func (this *Screen) RotateColumnByOne(colIndex int) {
    tmp := this.Pixels[5][colIndex]
    for i := 5; i > 0; i-- {
        this.Pixels[i][colIndex] = this.Pixels[i -1][colIndex]
    }
    this.Pixels[0][colIndex] = tmp
}

func (this *Screen) RotateColumn(colIndex int, shift int) {
    for ; shift > 0; shift -- {
        this.RotateColumnByOne(colIndex)
    }
}

func (this *Screen) EvalInstr(line string) bool {
    if strings.HasPrefix(line, "rect ") {
        size := strings.Split(line[5:], "x")
        if len(size) != 2 {
            return false
        }
        px, err := strconv.Atoi(size[0])
        if err != nil { return false }
        py, err := strconv.Atoi(size[1])
        if err != nil { return false }
        this.CreateRect(px, py)

    } else if (strings.HasPrefix(line, "rotate column x=")) {
        size := strings.Split(line[16:], " ")
        colIndex, err := strconv.Atoi(size[0])
        if err != nil { return false }
        rotateBy, err := strconv.Atoi(size[2])
        if err != nil { return false }
        this.RotateColumn(colIndex, rotateBy)

    } else if (strings.HasPrefix(line, "rotate row y=")) {
        size := strings.Split(line[13:], " ")
        rowIndex, err := strconv.Atoi(size[0])
        if err != nil { return false }
        rotateBy, err := strconv.Atoi(size[2])
        if err != nil { return false }
        this.RotateRows(rowIndex, rotateBy)

    } else {
        return false
    }
    return true
}

func (this Screen) CountOn() int {
    result := 0

    for i := 0; i < 6; i++ {
        for j := 0; j < 50; j++ {
            if this.Pixels[i][j] {
                result++
            }
        }
    }
    return result
}

func (this Screen) Dump() {
    for i := 0; i < 6; i++ {
        for j := 0; j < 50; j++ {
            if this.Pixels[i][j] {
                fmt.Printf("#")
            } else {
                fmt.Printf(".")
            }
        }
        fmt.Printf("\n")
    }
}

func main() {
    reader := bufio.NewReader(os.Stdin)
    scr := NewScreen()

    for true {
        line, err := reader.ReadString('\n')
        if len(line) > 0 {
            line = line[0: len(line) -1]
            if scr.EvalInstr(line) == false {
                fmt.Println("WTF instruction " +line)
                continue
            }
        }
        if (err != nil) {
            break
        }
    }
    scr.Dump()
    fmt.Println(scr.CountOn())
}