06

1 files changed, 68 insertions, 0 deletions

diff --git a/06/src/main.rs b/06/src/main.rs
new file mode 100644
index 0000000..fa48fb0
--- /dev/null
+++ b/06/src/main.rs
@@ -0,0 +1,68 @@
+use advent_lib::prelude::*;
+
+
+fn main() -> Result<()> {
+  let mut args = std::env::args();
+  if args.len() != 2 {
+    eprintln!("Usage: advent input");
+  }
+  let _ = args.next();
+  let filename = args.next().unwrap();
+
+  let input = advent_lib::read_lines_file(&filename)?;
+
+  let mut time_buckets = Vec::new();
+  for word in input[0].split(',') {
+    let time = word.parse::<i64>()?;
+    while time_buckets.len() <= time as usize {
+      time_buckets.push(0);
+    }
+    time_buckets[time as usize] += 1;
+  }
+
+  for _ in 0 .. 80 {
+    time_buckets = iterate(&time_buckets);
+  }
+
+  println!("{}", population_size(&time_buckets));
+
+  for _ in 80 .. 256 {
+    time_buckets = iterate(&time_buckets);
+  }
+
+  println!("{}", population_size(&time_buckets));
+
+  Ok(())
+}
+
+
+fn iterate(old_time_buckets: &Vec<i64>) -> Vec<i64> {
+  let mut new_time_buckets = Vec::new();
+
+  while new_time_buckets.len() <= 8 {
+    new_time_buckets.push(0);
+  }
+
+  for (i, n) in old_time_buckets.iter().enumerate() {
+    if i == 0 {
+      new_time_buckets[6] += n;
+      new_time_buckets[8] += n;
+    } else {
+      new_time_buckets[i - 1] += n;
+    }
+  }
+
+  new_time_buckets
+}
+
+
+fn population_size(time_buckets: &Vec<i64>) -> i64 {
+  let mut result = 0;
+
+  for n in time_buckets {
+    result += n;
+  }
+
+  result
+}
+