day1 and day2

src/lib.rs

@@ -0,0 +1,75 @@
+use aoc_runner_derive::{aoc_lib, aoc};
+
+#[aoc(day1, part1)]
+pub fn solve_d1_p1(input: &str) -> u64 {
+    let mut entries: Vec<u64> = input.split('\n').map(|x| x.parse().unwrap()).collect();
+    entries.sort();
+    for entry in &entries {
+        let needed = 2020 - entry;
+        if let Ok(idx) = entries.binary_search(&needed) {
+            return entry * entries[idx];
+        }
+    }
+    panic!("not found");
+}
+
+#[aoc(day1, part2)]
+pub fn solve_d1_p2(input: &str) -> Option<u64> {
+    let mut entries: Vec<u64> = input.split('\n').map(|x| x.parse().unwrap()).collect();
+    entries.sort();
+    for i in 0 .. entries.len()-2 {
+        let entry1 = entries[i];
+        for j in i+1 .. entries.len()-1 {
+            let entry2 = entries[j];
+            if entry1 + entry2 > 2020 {
+                break;
+            }
+            for k in j+1 .. entries.len() {
+                let entry3 = entries[k];
+                if entry1 + entry2 + entry3 == 2020 {
+                    return Some(entry1 * entry2 * entry3)
+                }
+            }
+        }
+    }
+    return None
+}
+
+#[aoc(day2, part1)]
+pub fn solve_d2_p1(input: &str) -> usize {
+    fn line_is_valid(mut line: &str) -> bool {
+        let lb_idx = line.find('-').unwrap();
+        let lb: usize = (&line[..lb_idx]).parse().unwrap();
+        line = &line[lb_idx+1..];
+
+        let ub_idx = line.find(' ').unwrap();
+        let ub: usize = (&line[..ub_idx]).parse().unwrap();
+        line = &line[ub_idx+1..];
+
+        let letter = line.as_bytes()[0];
+        let passwd = &line[3..];
+        let count = passwd.bytes().filter(|&b| b == letter).count();
+        count >= lb && count <= ub
+    }
+    input.split('\n').filter(|x| line_is_valid(x)).count()
+}
+
+#[aoc(day2, part2)]
+pub fn solve_d2_p2(input: &str) -> usize {
+    fn line_is_valid(mut line: &str) -> bool {
+        let lb_idx = line.find('-').unwrap();
+        let lb: usize = (&line[..lb_idx]).parse().unwrap();
+        line = &line[lb_idx+1..];
+
+        let ub_idx = line.find(' ').unwrap();
+        let ub: usize = (&line[..ub_idx]).parse().unwrap();
+        line = &line[ub_idx+1..];
+
+        let letter = line.as_bytes()[0];
+        let passwd = &line[3..].as_bytes();
+        (passwd[lb-1] == letter) ^ (passwd[ub-1] == letter)
+    }
+    input.split('\n').filter(|x| line_is_valid(x)).count()
+}
+
+aoc_lib!{ year = 2020 }