From: Neil Smith <neil.git@njae.me.uk>
Date: Tue, 18 Jul 2017 08:45:58 +0000 (+0100)
Subject: Done day 5 javascript
X-Git-Url: https://git.njae.me.uk/?p=ou-summer-of-code-2017.git;a=commitdiff_plain;h=47822cddf29c002717701d786b6f41ac02a73da0

Done day 5 javascript
---

diff --git a/05-display-board/day5.js b/05-display-board/day5.js
new file mode 100644
index 0000000..00a1e5d
--- /dev/null
+++ b/05-display-board/day5.js
@@ -0,0 +1,118 @@
+var fs = require("fs");
+
+const WIDTH = 80;
+const HEIGHT = 8;
+
+var initial_grid = new Array(HEIGHT);
+for (var i = 0; i < HEIGHT; i++) {
+  initial_grid[i] = new Array(WIDTH);
+  for (var j = 0; j < WIDTH; j++) {
+    initial_grid[i][j] = false;
+  }
+}
+
+function printGrid(g) {
+    return g.map(function (row) {
+        return row.map(showCell).join(''); 
+    }).join('\n');
+}
+
+function showCell(c) {
+    if (c) {
+        return '*';
+    } else {
+        return ' ';
+    }
+}
+
+// toggle the value of a cell
+function toggle(c) {
+    if (c) {
+        return false;
+    } else {
+        return true;
+    }
+}
+
+// turn a stirng into a command (a three-element array)
+function parseCommand(str) {
+    var command = str.split(' ').slice(-3);
+    command[1] = Number(command[1]);
+    command[2] = Number(command[2]);
+    return command;
+}
+
+// implement the instructions
+function top(from, to, grid) {
+    for (var c = from-1; c < to; c++) {
+        grid[0][c] = toggle(grid[0][c]);
+    };
+    return grid;
+}
+
+function left(from, to, grid) {
+    for (var r = from-1; r < to; r++) {
+        grid[r][0] = toggle(grid[r][0]);
+    };
+    return grid;
+}
+
+function rotate_column(col, raw_n, grid) {
+    var n = raw_n % HEIGHT;
+    var temp_column = new Array(HEIGHT);
+    for (var i = 0; i < HEIGHT; i++) {
+        temp_column[i] = grid[i][col-1];
+    };
+    var new_col = temp_column.slice(-n).concat(temp_column.slice(0, -n));
+    for (var i = 0; i < HEIGHT; i++) {
+        grid[i][col-1] = new_col[i];
+    };   
+    return grid;
+}
+
+function rotate_row(row, raw_n, grid) {
+    var n = raw_n % WIDTH;
+    var temp_row = new Array(WIDTH);
+    for (var i = 0; i < WIDTH; i++) {
+        temp_row[i] = grid[row-1][i];
+    };
+    var new_row = temp_row.slice(-n).concat(temp_row.slice(0, -n));
+    for (var i = 0; i < WIDTH; i++) {
+        grid[row-1][i] = new_row[i];
+    };
+    return grid;
+}
+
+
+// Dispatch table for execution
+var dispatchTable = {'top': top, 'left': left, 
+    'row': rotate_row, 'column': rotate_column};
+
+
+// Do one command, based on the function stored in the dispatch table
+function dispatchCommand(grid, command) {
+    return dispatchTable[command[0]](command[1], command[2], grid);
+}
+
+// Execute all the commands as a fold on the initial grid
+function executeCommands(commands, grid) {
+    return commands.reduce(dispatchCommand, grid);
+}
+
+
+// Merge the lines of the grid into one line, then pick out the true values
+function count_pixels(grid) {
+    return  grid.reduce(
+                function (t, l) {return t.concat(l);}
+            ).filter(
+                function (c) {return c;}
+            ).length
+}
+
+var instrs = fs.readFileSync('05-pixels.txt').toString().split('\n');
+var instructions = instrs.map(parseCommand);
+
+var final_grid = executeCommands(instructions, initial_grid);
+
+console.log(count_pixels(final_grid));
+console.log(printGrid(final_grid));