From c0068cb24059ffd7aaf8268f46363a7bb7e798d5 Mon Sep 17 00:00:00 2001
From: Abhijith <abchatra@microsoft.com>
Date: Mon, 27 Mar 2017 16:32:09 -0700
Subject: [PATCH] Game of life code card

---
 docs/examples.md                        |   8 +-
 docs/examples/gameofLife.md             | 124 ++++++++++++++++++++++++
 docs/projects/milk-carton-robot/code.md |   2 +-
 3 files changed, 132 insertions(+), 2 deletions(-)
 create mode 100644 docs/examples/gameofLife.md

diff --git a/docs/examples.md b/docs/examples.md
index 3181968b..f20c7d7e 100644
--- a/docs/examples.md
+++ b/docs/examples.md
@@ -19,7 +19,13 @@ Here are some fun programs for your @boardname@!
   "name": "Rando",
   "description": "Randomly blinking LEDs",
   "url":"/examples/rando"
-}]
+},
+{
+  "name": "Game of Life",
+  "description": "Simulation in LEDs (javascript)",
+  "url":"/examples/gameofLife"
+}
+]
 ```
 
 ## Sensors
diff --git a/docs/examples/gameofLife.md b/docs/examples/gameofLife.md
new file mode 100644
index 00000000..70b1f63b
--- /dev/null
+++ b/docs/examples/gameofLife.md
@@ -0,0 +1,124 @@
+# Game of Life simulation in LEDs
+
+```blocks
+//https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life
+let lifeChart: Image = null
+
+//Use button A for the next iteration of game of life
+input.onButtonPressed(Button.A, () => {
+    gameOfLife();
+    show();
+})
+
+//Use button B for reseting to random initial seed state
+input.onButtonPressed(Button.B, () => {
+    reset();
+    show();
+})
+
+lifeChart = images.createImage(`
+    . . . . .
+    . . . . .
+    . . . . .
+    . . . . .
+    . . . . .
+    `)
+
+//State holds the information about pixel is live or dead
+//false means dead, true means live.
+let state = [false, false, false, false, false,
+    false, false, false, false, false,
+    false, false, false, false, false,
+    false, false, false, false, false,
+    false, false, false, false, false]
+
+//get & set on any array
+function getState(arr: boolean[], x: number, y: number): boolean {
+    return arr[x * 5 + y];
+}
+function setState(arr: boolean[], x: number, y: number, value: boolean): void {
+    arr[x * 5 + y] = value;
+}
+
+//Generate random initial state.
+function reset() {
+    for (let x = 0; x < 5; x++) {
+        for (let y = 0; y < 5; y++) {
+            setState(state, x, y, Math.randomBoolean());
+        }
+    }
+}
+
+//Show the lifeChart based on the state
+function show() {
+    for (let x = 0; x < 5; x++) {
+        for (let y = 0; y < 5; y++) {
+            lifeChart.setPixel(x, y, getState(state, x, y));
+        }
+    }
+    lifeChart.plotImage(0);
+}
+
+//Core function
+function gameOfLife() {
+    let result: boolean[] = [];
+
+    for (let x = 0; x < 5; x++) {
+        for (let y = 0; y < 5; y++) {
+            let count = 0;
+
+            //Count the live cells in the next row
+            if ((x + 1) < 5) {
+                if (getState(state, x + 1, y)) {
+                    count++;
+                }
+                if ((y + 1 < 5) && getState(state, x + 1, y + 1)) {
+                    count++;
+                }
+                if ((y - 1 >= 0) && getState(state, x + 1, y - 1)) {
+                    count++;
+                }
+            }
+
+            //Count the live cells in the previous row
+            if ((x - 1) >= 0) {
+                if (getState(state, x - 1, y)) {
+                    count++;
+                }
+                if ((y + 1 < 5) && getState(state, x - 1, y + 1)) {
+                    count++;
+                }
+                if ((y - 1 >= 0) && getState(state, x - 1, y - 1)) {
+                    count++;
+                }
+            }
+
+            //Count the live cells in the current row exlcuding the current position.
+            if ((y - 1 >= 0) && getState(state, x, y - 1)) {
+                count++;
+            }
+            if ((y + 1 < 5) && getState(state, x, y + 1)) {
+                count++;
+            }
+
+            // Toggle live\dead cells based on the count.
+            // Any live cell with fewer than two live neighbours dies, as if caused by underpopulation.
+            // Any live cell with two or three live neighbours lives on to the next generation.
+            // Any dead cell with exactly three live neighbours becomes a live cell, as if by reproduction            
+            // Any live cell with more than three live neighbours dies, as if by overpopulation.
+            switch (count) {
+                case 0: setState(result, x, y, false); break;
+                case 1: setState(result, x, y, false); break;
+                case 2: setState(result, x, y, getState(state, x, y)); break;
+                case 3: setState(result, x, y, true); break;
+                default: setState(result, x, y, false); break;
+            }
+        }
+    }
+    //Update the state
+    state = result;
+}
+//Initial reset & show
+reset();
+show();
+```
\ No newline at end of file
diff --git a/docs/projects/milk-carton-robot/code.md b/docs/projects/milk-carton-robot/code.md
index 12786f97..839d9d54 100644
--- a/docs/projects/milk-carton-robot/code.md
+++ b/docs/projects/milk-carton-robot/code.md
@@ -68,6 +68,6 @@ closed = 175
 ```
 
 
-### ~button /projects/milk-jar-robot/connect
+### ~button /projects/milk-carton-robot/connect
 NEXT: Connect
 ### ~
\ No newline at end of file