day(01): add initial solution

Signed-off-by: Matej Focko <mfocko@redhat.com>

samples/day01.txt

@@ -0,0 +1,14 @@
+1000
+2000
+3000
+
+4000
+
+5000
+6000
+
+7000
+8000
+9000
+
+10000

src/bin/day01.rs

@@ -0,0 +1,88 @@
+use aoc_2022::file_to_lines;
+
+use tracing::*;
+use tracing_subscriber::EnvFilter;
+
+use std::cmp::max;
+
+struct Accum {
+    max_sum: i32,
+    current_sum: i32,
+}
+
+impl Accum {
+    fn new() -> Accum {
+        Accum {
+            max_sum: 0,
+            current_sum: 0,
+        }
+    }
+}
+
+fn part_1(input: &[i32]) -> i32 {
+    input
+        .iter()
+        .fold(Accum::new(), |a, &x| {
+            if x == -1 {
+                Accum {
+                    max_sum: max(a.max_sum, a.current_sum),
+                    current_sum: 0,
+                }
+            } else {
+                Accum {
+                    max_sum: a.max_sum,
+                    current_sum: a.current_sum + x,
+                }
+            }
+        })
+        .max_sum
+}
+
+fn part_2(input: &[i32]) -> i32 {
+    let mut calories: Vec<i32> = Vec::new();
+
+    let last_elf = input
+        .iter()
+        .fold(Accum::new(), |a, &x| {
+            if x == -1 {
+                calories.push(a.current_sum);
+                Accum::new()
+            } else {
+                Accum {
+                    max_sum: a.max_sum,
+                    current_sum: a.current_sum + x,
+                }
+            }
+        })
+        .current_sum;
+    calories.push(last_elf);
+
+    calories.sort();
+    calories.iter().rev().take(3).sum()
+}
+
+fn main() {
+    tracing_subscriber::fmt()
+        .with_env_filter(EnvFilter::from_default_env())
+        .with_target(false)
+        .with_file(true)
+        .with_line_number(true)
+        .without_time()
+        .compact()
+        .init();
+
+    let sample: Vec<i32> = file_to_lines("samples/day01.txt")
+        .iter()
+        .map(|s| if s.is_empty() { -1 } else { s.parse().unwrap() })
+        .collect();
+    let input: Vec<i32> = file_to_lines("inputs/day01.txt")
+        .iter()
+        .map(|s| if s.is_empty() { -1 } else { s.parse().unwrap() })
+        .collect();
+
+    assert_eq!(part_1(&sample), 24000);
+    info!("Part 1: {}", part_1(&input));
+
+    assert_eq!(part_2(&sample), 45000);
+    info!("Part 2: {}", part_2(&input));
+}