day 03

examples/day03_1.rs

@@ -0,0 +1,19 @@
+use std::collections::HashSet;
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let lines: Vec<String> = std::io::stdin().lines().map(|x| x.unwrap()).collect();
+    let mut result = 0;
+    for line in lines {
+        let chars: Vec<char> = line.chars().collect();
+        let a: HashSet<char> = (chars[0..chars.len()/2]).iter().map(|x| *x).collect();
+        let b: HashSet<char> = (chars[chars.len()/2..]).iter().map(|x| *x).collect();
+        let c = *a.intersection(&b).next().unwrap();
+        result += match c {
+            'a'..='z' => (c as u32) - ('a' as u32) + 1,
+            'A'..='Z' => (c as u32) - ('A' as u32) + 27,
+            _ => todo!(),
+        };
+    }
+    println!("{:?}", result);
+    Ok(())
+}

examples/day03_2.rs

@@ -0,0 +1,20 @@
+use std::collections::HashSet;
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let lines: Vec<String> = std::io::stdin().lines().map(|x| x.unwrap()).collect();
+    let mut result = 0;
+    for window in lines.chunks(3) {
+        let a: HashSet<char> = (window[0]).chars().collect();
+        let b: HashSet<char> = (window[1]).chars().collect();
+        let c: HashSet<char> = (window[2]).chars().collect();
+        let d: HashSet<char> = a.intersection(&b).map(|x| *x).collect();
+        let mut e = d.intersection(&c);
+        result += match *e.next().unwrap() {
+            w @ 'a'..='z' => (w as u32) - ('a' as u32) + 1,
+            w @ 'A'..='Z' => (w as u32) - ('A' as u32) + 27,
+            _ => todo!(),
+        };
+    }
+    println!("{:?}", result);
+    Ok(())
+}