Add solution to day 1

2 files changed, 99 insertions, 0 deletions

diff --git a/src/day_1.rs b/src/day_1.rs
new file mode 100644
index 0000000..6632baa
--- /dev/null
+++ b/src/day_1.rs
@@ -0,0 +1,47 @@
+pub fn run(input: Vec<String>)
+{
+    // Convert inputs to unsigned integer numbers
+    let input: Vec<u32> = input
+        .into_iter()
+        .map(|s| {
+            s.parse()
+                .expect("All lines are required to be unsigned integers")
+        })
+        .collect();
+
+    part1(&input);
+    part2(&input);
+}
+
+fn part1(input: &[u32])
+{
+    let mut last_depth = u32::MAX;
+    let num_down_slopes = input
+        .iter()
+        .filter(|&depth| {
+            let going_deeper = *depth > last_depth;
+            last_depth = *depth;
+
+            going_deeper
+        })
+        .count();
+
+    println!("Solution to part 1: {}", num_down_slopes);
+}
+
+fn part2(input: &[u32])
+{
+    let mut last_aliased_depth = u32::MAX;
+    let num_aliased_down_slopes = input
+        .windows(3)
+        .filter(|&depths| {
+            let aliased_depth: u32 = depths.iter().sum();
+            let going_deeper = aliased_depth > last_aliased_depth;
+            last_aliased_depth = aliased_depth;
+
+            going_deeper
+        })
+        .count();
+
+    println!("Solution to part 2: {}", num_aliased_down_slopes);
+}
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..c45571e
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,52 @@
+mod day_1;
+
+use std::fs::File;
+use std::io::{BufRead, BufReader};
+use std::path::PathBuf;
+use std::str::FromStr;
+
+use argparse::{ArgumentParser, Store};
+
+fn read_input(day: u8) -> Vec<String>
+{
+    let file_name = PathBuf::from_str("input")
+        .unwrap()
+        .join(format!("day_{}.txt", day));
+    let input_file =
+        File::open(&file_name).expect(&format!("Unable to open input file {:?}", file_name));
+    let reader = BufReader::new(input_file);
+
+    reader
+        .lines()
+        .map(|r| r.expect("Unable to read line in input file"))
+        .collect()
+}
+
+fn run(day: u8, input: Vec<String>)
+{
+    match day {
+        1 => day_1::run(input),
+        o => panic!("Day {} is not implemented (yet)", o),
+    }
+}
+
+fn main()
+{
+    let mut day: u8 = 1;
+    {
+        let mut ap = ArgumentParser::new();
+        ap.set_description("Run advent of code 2015 solvers");
+
+        ap.refer(&mut day).add_option(
+            &["-d", "--day"],
+            Store,
+            "The day of the month of which the solver should be run",
+        );
+
+        ap.parse_args_or_exit();
+    }
+
+    println!("Attempting to solve day {}", day);
+    let input = read_input(day);
+    run(day, input);
+}