From 2971f6c52f08abf850037eb1d70554ecee5967ec Mon Sep 17 00:00:00 2001
From: Elis Hirwing <elis@hirwing.se>
Date: Mon, 4 Dec 2017 20:36:45 +0100
Subject: [PATCH] [2017-12-03] Solutions for both puzzles

---
 Makefile      |   2 +
 day3/main.php | 116 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 118 insertions(+)
 create mode 100644 day3/main.php

diff --git a/Makefile b/Makefile
index b1863c0..a8c5e17 100644
--- a/Makefile
+++ b/Makefile
@@ -7,6 +7,8 @@ day2:
 	php day2/main.php
 
 day3:
+	php day3/main.php
+
 day4:
 day5:
 day6:
diff --git a/day3/main.php b/day3/main.php
new file mode 100644
index 0000000..22142e6
--- /dev/null
+++ b/day3/main.php
@@ -0,0 +1,116 @@
+<?php
+// https://adventofcode.com/2017/day/3
+
+/*
+ * Working solution for 2017-12-03 part 1
+ */
+function puzzle1(int $maxNumber) : int
+{
+    $x = 0;
+    $y = 0;
+    $steps = 0;
+    $diameter = 1;
+    $direction = 4;
+
+    for ($number = 1; $number < $maxNumber; $number++) {
+        if ($direction === 4) {
+            $x++;
+            $diameter += 2;
+            $direction = 0;
+            $steps = $diameter - 2;
+        } else {
+            switch ($direction) {
+                case 0:
+                    $y--;
+                    break;
+
+                case 1:
+                    $x--;
+                    break;
+
+                case 2:
+                    $y++;
+                    break;
+
+                case 3:
+                    $x++;
+                    break;
+            }
+
+            $steps--;
+
+            if ($steps === 0) {
+                $direction++;
+                $steps = $diameter - 1;
+            }
+        }
+    }
+
+    return abs($x) + abs($y);
+}
+
+/*
+ * Working solution for 2017-12-03 part 2
+ */
+function puzzle2(int $maxNumber) : int
+{
+    $x = 0;
+    $y = 0;
+    $steps = 0;
+    $diameter = 1;
+    $direction = 4;
+    $map = [];
+
+    for ($number = 1; $number < $maxNumber; $number++) {
+        //  x-1,y-1   x,y-1   x+1,y-1
+        //  x-1,y             x+1,y+1
+        //  x-1,y+1   x,y+1   x+1,y+1
+        $newNumber =
+            ($map[$y-1][$x-1] ?? 0) +
+            ($map[$y-1][$x]   ?? 0) +
+            ($map[$y-1][$x+1] ?? 0) +
+            ($map[$y][$x-1]   ?? 0) +
+            ($map[$y][$x+1]   ?? 0) +
+            ($map[$y+1][$x-1] ?? 0) +
+            ($map[$y+1][$x]   ?? 0) +
+            ($map[$y+1][$x+1] ?? 0);
+
+        $number = ($newNumber === 0) ? 1 : $newNumber;
+
+        $map[$y][$x] = $number;
+
+        if ($direction === 4) {
+            $x++;
+            $diameter += 2;
+            $direction = 0;
+            $steps = $diameter - 2;
+        } else {
+            switch ($direction) {
+                case 0:
+                    $y--;
+                    break;
+
+                case 1:
+                    $x--;
+                    break;
+
+                case 2:
+                    $y++;
+                    break;
+
+                case 3:
+                    $x++;
+                    break;
+            }
+
+            $steps--;
+
+            if ($steps === 0) {
+                $direction++;
+                $steps = $diameter - 1;
+            }
+        }
+    }
+
+    return $number - 1;
+}