From 52fe8eb76f72992dcea759e3fa88f90f092c67b0 Mon Sep 17 00:00:00 2001
From: Wesley Moore <wes@wezm.net>
Date: Sun, 8 Dec 2019 16:23:51 +1100
Subject: [PATCH] Day 8 part 2

---
 2019/src/bin/day8.rs | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/2019/src/bin/day8.rs b/2019/src/bin/day8.rs
index 30dc87c..cfb8c4e 100644
--- a/2019/src/bin/day8.rs
+++ b/2019/src/bin/day8.rs
@@ -18,9 +18,32 @@ fn main() -> io::Result<()> {
 
     println!("Part 1: {}", ones * twos);
 
+    let picture = composite(&layers);
+
+    for i in 0..(WIDTH * HEIGHT) {
+        if i % WIDTH == 0 {
+            println!();
+        }
+        let pixel = if picture[i] == '1' { '█' } else { ' ' };
+        print!("{}", pixel);
+    }
+    println!();
+
     Ok(())
 }
 
 fn count_digits(layer: &[char], digit: char) -> usize {
     layer.iter().filter(|&&c| c == digit).count()
 }
+
+fn composite(layers: &Vec<&[char]>) -> Vec<char> {
+    let mut image = Vec::with_capacity(WIDTH * HEIGHT);
+    // For each pixel go top to bottom finding the first non-transparent colour and add that to the
+    // final image.
+    for i in 0..(WIDTH * HEIGHT) {
+        let layer = layers.iter().find(|layer| layer[i] != '2').unwrap();
+        image.push(layer[i]);
+    }
+
+    image
+}