From 6a23bbad3b1dbadaa41e2172dc4257915156cf18 Mon Sep 17 00:00:00 2001
From: Anders Olsson <anders.e.olsson@gmail.com>
Date: Mon, 17 Dec 2018 14:02:49 +0100
Subject: [PATCH] 2018/06

---
 2018/06/Cargo.lock     |   4 ++
 2018/06/example-01.txt |   6 +++
 2018/06/input.txt      |  50 ++++++++++++++++++
 2018/06/src/main.rs    | 116 ++++++++++++++++++++++++++++++++++++++++-
 4 files changed, 174 insertions(+), 2 deletions(-)
 create mode 100644 2018/06/Cargo.lock
 create mode 100644 2018/06/example-01.txt
 create mode 100644 2018/06/input.txt

diff --git a/2018/06/Cargo.lock b/2018/06/Cargo.lock
new file mode 100644
index 0000000..c87e1a0
--- /dev/null
+++ b/2018/06/Cargo.lock
@@ -0,0 +1,4 @@
+[[package]]
+name = "day-06"
+version = "0.1.0"
+
diff --git a/2018/06/example-01.txt b/2018/06/example-01.txt
new file mode 100644
index 0000000..95d160a
--- /dev/null
+++ b/2018/06/example-01.txt
@@ -0,0 +1,6 @@
+1, 1
+1, 6
+8, 3
+3, 4
+5, 5
+8, 9
diff --git a/2018/06/input.txt b/2018/06/input.txt
new file mode 100644
index 0000000..7cf5491
--- /dev/null
+++ b/2018/06/input.txt
@@ -0,0 +1,50 @@
+194, 200
+299, 244
+269, 329
+292, 55
+211, 63
+123, 311
+212, 90
+292, 169
+359, 177
+354, 95
+101, 47
+95, 79
+95, 287
+294, 126
+81, 267
+330, 78
+202, 165
+225, 178
+266, 272
+351, 326
+180, 62
+102, 178
+151, 101
+343, 145
+205, 312
+74, 193
+221, 56
+89, 89
+242, 172
+59, 138
+83, 179
+223, 88
+297, 234
+147, 351
+226, 320
+358, 338
+321, 172
+54, 122
+263, 165
+126, 341
+64, 132
+264, 306
+72, 202
+98, 49
+238, 67
+310, 303
+277, 281
+222, 318
+357, 169
+123, 225
diff --git a/2018/06/src/main.rs b/2018/06/src/main.rs
index e7a11a9..2466f17 100644
--- a/2018/06/src/main.rs
+++ b/2018/06/src/main.rs
@@ -1,3 +1,115 @@
-fn main() {
-    println!("Hello, world!");
+use std::collections::HashMap;
+use std::io::{self, BufRead};
+
+fn distance(a: (i32, i32), b: (i32, i32)) -> i32 {
+    (a.0 - b.0).abs() + (a.1 - b.1).abs()
+}
+
+#[derive(Clone, Copy, Debug)]
+enum State {
+    Empty,
+    Owner(usize, i32),
+    Equal(i32),
+}
+
+#[derive(Clone, Copy, Debug)]
+enum Area {
+    Infinite,
+    Finite(usize),
+}
+
+fn main() {
+    let coordinates = io::stdin()
+        .lock()
+        .lines()
+        .filter_map(Result::ok)
+        .map(|line| {
+            let coords = line
+                .split(", ")
+                .map(|coord| coord.parse::<i32>().unwrap())
+                .collect::<Vec<_>>();
+
+            (coords[0], coords[1])
+        })
+        .collect::<Vec<_>>();
+
+    let width = coordinates
+        .iter()
+        .map(|(x, _)| *x as usize)
+        .max().expect("failed to find max x") + 1;
+
+    let height = coordinates
+        .iter()
+        .map(|(_, y)| *y as usize)
+        .max()
+        .expect("failed to find max y") + 1;
+
+    let mut grid_view = vec![State::Empty; width * height].into_boxed_slice();
+
+    for x in 0..width {
+        for y in 0..height {
+            for (i, c) in coordinates.iter().enumerate() {
+                let distance = distance(*c, (x as i32, y as i32));
+                let state = &mut grid_view[x + (y * width)];
+
+                *state = match state {
+                    State::Empty => State::Owner(i, distance),
+                    State::Owner(_, d) if *d > distance => State::Owner(i, distance),
+                    State::Owner(o, d) if *d == distance && *o != i => State::Equal(distance),
+                    State::Equal(d) if *d > distance => State::Owner(i, distance),
+                    _ => *state,
+                };
+            }
+        }
+    }
+
+    let mut areas = HashMap::new();
+
+    for x in 0..width {
+        for y in 0..height {
+            if let State::Owner(o, _) = grid_view[x + (y * width)] {
+                let a = areas.entry(o).or_insert(Area::Finite(0));
+
+                if x == 0 || x == width - 1 || y == 0 || y == height - 1 {
+                    *a = Area::Infinite;
+                } else {
+                    match a {
+                        Area::Infinite => (),
+                        Area::Finite(area) => *area += 1,
+                    }
+                }
+            }
+        }
+    }
+
+    let (_, area) = areas
+        .iter()
+        .filter_map(|(i, area)| if let Area::Finite(area) = area {
+            Some((i, area))
+        } else {
+            None
+        })
+        .max_by_key(|(_, area)| *area)
+        .expect("failed to find max area");
+
+    println!("part.one={}", area);
+
+    let mut grid_view = vec!['.'; width * height].into_boxed_slice();
+
+    for y in 0..height {
+        for x in 0..width {
+            let total = coordinates
+                .iter()
+                .map(|c| distance(*c, (x as i32, y as i32)))
+                .sum::<i32>();
+
+            if total < 10_000 {
+                grid_view[x + (y * width)] = '#';
+            }
+        }
+    }
+
+    let area = grid_view.iter().filter(|r| **r == '#').count();
+
+    println!("part.two={}", area);
 }