Day 2

02/part1.rs

@@ -0,0 +1,48 @@
+use std::collections::HashMap;
+use std::error::Error;
+use std::fs::File;
+use std::io::BufReader;
+use std::io::prelude::*;
+
+fn main() -> std::io::Result<()> {
+    let file = match File::open("input") {
+        Err(why) => panic!("couldn't open input: {}", Error::description(&why)),
+        Ok(file) => file,
+    };
+
+    let reader = BufReader::new(file);
+    let lines = reader.lines();
+
+    for result in lines {
+        let l = result.unwrap();
+        let mut freq = HashMap::new();
+        let mut is2 = false;
+        let mut is3 = false;
+
+        for ch in l.chars() {
+            let count = freq.entry(ch).or_insert(0);
+            *count += 1;
+        }
+
+        for (_ch, count) in freq {
+            if count == 2 {
+                is2 = true;
+            }
+            if count == 3 {
+                is3 = true;
+            }
+        }
+
+        if is2 {
+            count2+=1;
+        }
+        
+        if is3 {
+            count3+=1;
+        }
+    }
+
+    println!("2: {} 3: {} 2*3: {}", count2, count3, count2 * count3);
+
+    Ok(())
+}