d12

d12/input

@@ -0,0 +1,34 @@
+initial state: #..####.##..#.##.#..#.....##..#.###.#..###....##.##.#.#....#.##.####.#..##.###.#.......#............
+
+##... => .
+##.## => .
+.#.#. => #
+#..#. => .
+#.### => #
+.###. => .
+#.#.. => .
+##..# => .
+..... => .
+...#. => .
+.#..# => .
+####. => #
+...## => #
+..### => #
+#.#.# => #
+###.# => #
+#...# => #
+..#.# => .
+.##.. => #
+.#... => #
+.##.# => #
+.#### => .
+.#.## => .
+..##. => .
+##.#. => .
+#.##. => .
+#..## => .
+###.. => .
+....# => .
+##### => #
+#.... => .
+..#.. => #

d12/main.js

@@ -0,0 +1,97 @@
+
+function read(cb) {
+    require("fs").readFile('./input', 'utf8', (err, data) => {
+        var world = new World();
+        data.split("\n").forEach((l) => {
+            if (l.startsWith("initial state: ")) {
+                world.initializeState(l.substr(15));
+            } else {
+                var r = /([.#]+) => ([.#])/.exec(l);
+                if (r)
+                    world.rules[r[1]] = r[2];
+            }
+        });
+        cb(world);
+    });
+}
+
+function World() {
+    this.initialState = [];
+    this.rules = [];
+    this.state = [];
+    this.loop = 0;
+    this.offset = 0;
+}
+
+World.prototype.initializeState = function(li) {
+    for (var i =0, len = li.length; i < len; ++i)
+        this.initialState.push(li[i] == '#');
+    this.state = this.initialState;
+}
+
+World.prototype.arrToString = function(pos) {
+    var result = "";
+    for (var i =-2; i <= 2; ++i)
+        result += (this.initialState[pos +i] ? '#' : '.');
+    return result;
+}
+
+World.prototype.step = function() {
+    this.state = [];
+    var offset = [];
+    for (var i =-2; i < 0; ++i) {
+        var state = this.rules[this.arrToString(i)];
+        if (state == '#')
+            offset[-i] = true;
+        else if (state == '.')
+            offset[-i] = false;
+    }
+    for (var i =0, len = this.initialState.length +2; i < len; ++i) {
+        var state = this.rules[this.arrToString(i)];
+        if (state == '#')
+            this.state[i] = true;
+        else if (state == '.')
+            this.state[i] = false;
+    }
+    if (offset[2]) {
+        this.state.splice(0, 0, offset[2], offset[1])
+        this.offset += 2;
+    }
+    else if (offset[1]) {
+        this.state.splice(0, 0, offset[1])
+        ++this.offset;
+    }
+    this.initialState = this.state;
+    ++this.loop;
+}
+
+World.prototype.count = function() {
+    var result = 0;
+    for (var i =0, len = this.initialState.length; i < len; ++i)
+        if (this.initialState[i])
+            result += i -this.offset;
+    return result;
+}
+
+World.prototype.run = function(max) {
+    for (var i =0; i < max; ++i)
+        this.step();
+}
+
+function ex1() {
+    read(world => {
+        world.run(20);
+        console.log(world.count());
+    });
+}
+
+function ex2() {
+    read(world => {
+        world.run(500);
+        console.log(world.count() +(50000000000 -500) *36);
+    });
+}
+
+ex1();
+ex2();
+