d10p2

day10/src/main.rs

@@ -26,7 +26,7 @@ fn parse_line(line: String) -> Result<Inst, ParseError> {
 fn main() {
     let file = File::open(&env::args().nth(1).unwrap()).unwrap();
     let reader = io::BufReader::new(file);
-    let mut xs: Vec<i64> = vec![0, 1];
+    let mut xs: Vec<i64> = vec![1];
 
     for line in reader.lines().flatten() {
         let last_x = *xs.last().unwrap();
@@ -36,10 +36,12 @@ fn main() {
             Err(e) => { eprintln!("error: {:?}", e); process::exit(1) },
         }
     }
-    let res: i64 = xs.iter().enumerate()
-        .skip(20).step_by(40)
-        .map(|(i, &x)| (i as i64)*x)
-        .sum();
-    println!("{:?}", res);
+
+    let screen: Vec<_> = xs.iter().enumerate()
+        .map(|(i, &x)| if ((i as i64) % 40 - x).abs() <= 1 { '#' } else { '.' })
+        .collect();
+    for i in 0..6 {
+        println!("{}", screen[(i*40)..((i+1)*40)].iter().collect::<String>());
+    }
 }
 

day10/src/main1.rs

@@ -0,0 +1,45 @@
+use std::env;
+use std::process;
+use std::fs::File;
+use std::io::{self, BufRead};
+
+#[derive(Debug)]
+enum Inst{
+    AddX(i64),
+    Noop,
+}
+
+#[derive(Debug)]
+struct ParseError(String);
+
+fn parse_line(line: String) -> Result<Inst, ParseError> {
+    match &line[..4] {
+        "noop" => Ok(Inst::Noop),
+        "addx" => match line[5..].parse::<i64>() {
+            Ok(operand) => Ok(Inst::AddX(operand)),
+            Err(e) => Err(ParseError(e.to_string())),
+        },
+        _ => Err(ParseError(String::from("bad instruction"))),
+    }
+}
+
+fn main() {
+    let file = File::open(&env::args().nth(1).unwrap()).unwrap();
+    let reader = io::BufReader::new(file);
+    let mut xs: Vec<i64> = vec![0, 1];
+
+    for line in reader.lines().flatten() {
+        let last_x = *xs.last().unwrap();
+        match parse_line(line) {
+            Ok(Inst::Noop) => { xs.push(last_x) },
+            Ok(Inst::AddX(x)) => { xs.push(last_x); xs.push(last_x + x) },
+            Err(e) => { eprintln!("error: {:?}", e); process::exit(1) },
+        }
+    }
+    let res: i64 = xs.iter().enumerate()
+        .skip(20).step_by(40)
+        .map(|(i, &x)| (i as i64)*x)
+        .sum();
+    println!("{:?}", res);
+}
+