From 370c7bd70a5257e0b30189f150d0ee882bbac7c2 Mon Sep 17 00:00:00 2001
From: Justin Worthe <justin.worthe@gmail.com>
Date: Fri, 16 Dec 2016 09:59:13 +0200
Subject: AOC16

---
 aoc16/Cargo.lock  |  4 ++++
 aoc16/Cargo.toml  |  6 +++++
 aoc16/src/main.rs | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 78 insertions(+)
 create mode 100644 aoc16/Cargo.lock
 create mode 100644 aoc16/Cargo.toml
 create mode 100644 aoc16/src/main.rs

diff --git a/aoc16/Cargo.lock b/aoc16/Cargo.lock
new file mode 100644
index 0000000..af71beb
--- /dev/null
+++ b/aoc16/Cargo.lock
@@ -0,0 +1,4 @@
+[root]
+name = "aoc16"
+version = "0.1.0"
+
diff --git a/aoc16/Cargo.toml b/aoc16/Cargo.toml
new file mode 100644
index 0000000..3e56892
--- /dev/null
+++ b/aoc16/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "aoc16"
+version = "0.1.0"
+authors = ["Justin Worthe <justin.worthe@gmail.com>"]
+
+[dependencies]
diff --git a/aoc16/src/main.rs b/aoc16/src/main.rs
new file mode 100644
index 0000000..c5ecd10
--- /dev/null
+++ b/aoc16/src/main.rs
@@ -0,0 +1,68 @@
+fn main() {
+    let data = initial();
+    let expanded = expand_to_size(data, 35651584);
+    let check = checksum(expanded);
+    print(&check);
+}
+
+fn initial() -> Vec<bool> {
+    to_bit_vec("10001001100000001")
+}
+
+fn to_bit_vec(input: &str) -> Vec<bool> {
+    input.chars().map(|c| c == '1').collect()
+}
+
+fn expand(a: Vec<bool>) -> Vec<bool> {
+    let mut b = a.clone();
+    b.reverse();
+    b = b.iter().map(|x| !x).collect();
+
+    let mut out = a.clone();
+    out.push(false);
+    out.append(&mut b);
+    out
+}
+
+fn expand_to_size(init: Vec<bool>, size: usize) -> Vec<bool> {
+    let mut out = init.clone();
+    while out.len() < size {
+        out = expand(out);
+    }
+    out.truncate(size);
+    out
+}
+
+fn checksum(data: Vec<bool>) -> Vec<bool> {
+    let mut check: Vec<bool> = data.chunks(2).map(|x| x[0] == x[1]).collect();
+    if check.len() % 2 == 0 {
+        check = checksum(check);
+    }
+    check
+}
+
+fn print(data: &Vec<bool>) {
+    for &bit in data {
+        print!("{}", if bit {'1'} else {'0'});
+    }
+    println!("");
+}
+
+#[test]
+fn test_expand() {
+    assert_eq!(expand(to_bit_vec("1")), to_bit_vec("100"));
+    assert_eq!(expand(to_bit_vec("0")), to_bit_vec("001"));
+    assert_eq!(expand(to_bit_vec("11111")), to_bit_vec("11111000000"));
+    assert_eq!(expand(to_bit_vec("111100001010")), to_bit_vec("1111000010100101011110000"));
+}
+
+#[test]
+fn test_expand_to_size() {
+    assert_eq!(expand_to_size(to_bit_vec("10000"), 20), to_bit_vec("10000011110010000111"));
+}
+
+#[test]
+fn test_checksum() {
+    assert_eq!(checksum(to_bit_vec("10000011110010000111")), to_bit_vec("01100"));
+}
+
-- 
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