Day 2

src/day1.rs

@@ -17,7 +17,7 @@ pub fn solve_part1(input: &Vec<usize>) -> usize {
             }
         }
     }
-    unimplemented!();
+    panic!("No pair summed to 20202!");
 }
 
 
@@ -36,5 +36,5 @@ pub fn solve_part2(input: &Vec<usize>) -> usize {
             }
         }
     }
-    unimplemented!();
+    panic!("No triplet summed to 20202!");
 }

src/day2.rs

@@ -0,0 +1,68 @@
+use aoc_runner_derive::{aoc,aoc_generator};
+
+#[derive(Debug,PartialEq,Eq,Ord,PartialOrd)]
+pub struct Rule {
+    min: usize,
+    max: usize,
+    ch: char,
+    pw: String
+}
+
+impl Rule {
+    fn is_valid_part1(&self) -> bool {
+        let n=self.pw.chars().filter(|c| *c==self.ch).count();
+        return n>=self.min && n<=self.max;
+    }
+    fn is_valid_part2(&self) -> bool {
+        let idx_1=self.min-1;
+        let idx_2=self.max-1;
+        let chars: Vec<char> = self.pw.chars().collect();
+        return (chars.get(idx_1)==Some(&self.ch))^(chars.get(idx_2)==Some(&self.ch))
+    }
+}
+
+#[aoc_generator(day2)]
+pub fn input_generator(input: &str) -> Vec<Rule> {
+    input.lines().map(|l| {
+        let mut ws = l.trim().split_whitespace();
+        let range= ws.next().unwrap();
+        let ch= ws.next().unwrap().trim_end_matches(|c| c==':').chars().next().unwrap();
+        let pw= ws.next().unwrap().to_owned();
+        let (r_min, r_max) = {
+            let mut r=range.split('-');
+            let r_min=r.next().unwrap().parse().unwrap();
+            let r_max=r.next().unwrap().parse().unwrap();
+            (r_min,r_max)
+        };
+        Rule {
+            min:r_min,
+            max:r_max,
+            ch,
+            pw
+        }
+    }).collect::<Vec<Rule>>()
+}
+
+#[aoc(day2, part1)]
+pub fn solve_part1(input: &Vec<Rule>) -> usize {
+    let mut total=0;
+    for rule in input {
+        if rule.is_valid_part1() {
+            total+=1;
+        }
+    }
+    total
+}
+
+
+#[aoc(day2, part2)]
+pub fn solve_part2(input: &Vec<Rule>) -> usize {
+    let mut total=0;
+    for rule in input {
+        if rule.is_valid_part2() {
+            total+=1;
+        }
+    }
+    total
+}
+

src/lib.rs

@@ -1,3 +1,4 @@
 use aoc_runner_derive::aoc_lib;
 pub mod day1;
+pub mod day2;
 aoc_lib! { year = 2020 }