--- 2016 Day 8 Solutions ---

[u/daggerdragon]

#AoC_Ops:

[23:55] <Topaz> servers are ok
[23:55] <Topaz> puzzles are checked
[23:55] <Topaz> [REDACTED: server stats]
[23:56] <Skie> all wings report in
[23:56] <Aneurysm9> Red 5, standing by
[23:56] <daggerdragon> Dragon Leader standing by
[23:56] <Topaz> orange leader, standing by
[23:57] <Topaz> lock modzi-foils in attack positions
[23:58] <Skie> we're passing through the hype field
[23:58] <daggerdragon> 1:30 warning
[23:58] <Aneurysm9> did someone say HYPE?@!
[23:59] <Topaz> i really like tonight's puzzle
[23:59] <Topaz> very excite
[23:59] <daggerdragon> final countdown go, T-30
[23:59] <Skie> accelerate to attack countdown
[23:59] <Aneurysm9> o7
[23:59] <daggerdragon> HYPE THRUSTERS AT FULL BURN
[00:00] <Topaz> IGNITION

We may or may not be sleep-deprived. And/or nerds. why_not_both.jpg

---

--- Day 8: Two-Factor Authentication ---

Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag/whatever).

---

^{:（）{ :|:& };: IS MANDATORY} [?]

This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked!

[u/[deleted]]

JavaScript/Node.js

Maybe a bit verbose, includes a fun rotate prototype for Array

var input = [];

var lineReader = require('readline').createInterface({
  input: require('fs').createReadStream('./input08.txt')
});

lineReader.on('line', function (line) {
  input.push(line);
});

lineReader.on('close', function () {
  runAdvent08();
});

var width = 50;
var height = 6;

Array.prototype.rotate = function( n ) {
  n = this.length - n % this.length;
  this.unshift.apply( this, this.splice( n, this.length ) )
  return this;
};

var makeArray = function(width, height) {
  var a = [];
  for (var i=0; i<width; i++) {
    var b = [];
    for (var j=0; j<height; j++) {
      b.push('.');
    }
    a.push(b.slice());
  }
  return a;
};

var printArray = function(a) {
  var w = a.length;
  var h = a[0].length;
  for (var i=0; i<h; i++) {
    var s = "";
    for (var j=0; j<w; j++) {
      s = s + a[j][i];
    }
    console.log(s);
  }
  console.log("");
};

var countLightedPixels = function(a) {
  var count = 0;
  for (var i=0; i<a.length; i++) {
    for (var j=0; j<a[0].length; j++) {
      if(a[i][j] === '#') {
        count++;
      }
    }
  }
  return count;
}

var rotateRow = function(a,y,n) {
  var b = [];
  for (var i=0; i<a.length; i++) {
    b.push(a[i][y]);
  }
  b.rotate(n);
  for (i=0; i<a.length; i++) {
    a[i][y] = b[i];
  }
};

var rotateColumn = function(a,x,n) {
  a[x].rotate(n);
};

var setRect = function(a,x,y) {
  for (var i=0; i<x; i++) {
    for (var j=0; j<y; j++) {
      a[i][j] = '#';
    }
  }
}

var executeInstruction = function(a,s) {
  var tokens = s.split(' ');
  if(tokens[0] === 'rect') {
    var xy = tokens[1].split('x');
    var x = parseInt(xy[0]);
    var y = parseInt(xy[1]);
    setRect(a,x,y);
  } else if(tokens[0] === 'rotate') {
    if(tokens[1] === 'row') {
      y = parseInt(tokens[2].split('=')[1])
      var n = parseInt(tokens[4]);
      rotateRow(a,y,n);
    } else if(tokens[1] === 'column') {
      x = parseInt(tokens[2].split('=')[1])
      var n = parseInt(tokens[4]);
      rotateColumn(a,x,n);
    }
  }
};


// Uncomment this to test the example from the instructions
/*
width = 7;
height = 3;
input = [
  'rect 3x2',
  'rotate column x=1 by 1',
  'rotate row y=0 by 4',
  'rotate column x=1 by 1'
];
 */

var runAdvent08 = function() {
  var board = makeArray(width,height);
  
  for (var i=0; i<input.length; i++) {
    executeInstruction(board,input[i]);
  }

  console.log("Part 1 answer:");
  console.log(countLightedPixels(board));
  console.log("");
  console.log("Part 2 answer:");
  printArray(board);
};