complete day 10 part 2

src/main.rs

@@ -3,19 +3,18 @@ use std::io::{BufRead, BufReader};
 
 const FILENAME: &str = "data/input.txt";
 
-fn process_lines(reader: impl BufRead) -> anyhow::Result<i64> {
-    let mut register = 1_i64;
+fn process_lines(reader: impl BufRead) -> anyhow::Result<()> {
+    let mut sprite_column = 1_i64;
     let mut cycle = 0_usize;
-    let cycle_query = [19_usize, 59, 99, 139, 179, 219];
-    let mut signal_sum = 0;
+    let mut is_pixel_bright = [false; 240];
     for line_result in reader.lines() {
         let line = line_result?;
         let cost = if "noop" == line { 1 } else { 2 };
 
         for i_cycle in cycle..(cycle + cost) {
-            if cycle_query.binary_search(&i_cycle).is_ok() {
-                signal_sum += (1 + i_cycle as i64) * register;
-            }
+            is_pixel_bright[i_cycle] = (-1..=1)
+                .map(|i_sprite| i_sprite + sprite_column)
+                .any(|i_sprite| (i_cycle as i64 % 40) == i_sprite);
         }
 
         cycle += cost;
@@ -25,11 +24,28 @@ fn process_lines(reader: impl BufRead) -> anyhow::Result<i64> {
                 .next()
                 .and_then(|add_str| add_str.parse().ok())
                 .ok_or_else(|| anyhow::Error::msg("failed to read addend."))?;
-            register += addend;
+            sprite_column += addend;
         }
     }
 
-    Ok(signal_sum)
+    let display_buffer: Vec<char> = is_pixel_bright
+        .into_iter()
+        .map(|is_bright| if is_bright { '#' } else { '.' })
+        .collect();
+    (0usize..6)
+        .map(|i_row| {
+            let i_start = i_row * 40;
+            let i_end = i_start + 40;
+            i_start..i_end
+        })
+        .for_each(|line_indices| {
+            println!(
+                "{}",
+                display_buffer[line_indices].iter().collect::<String>()
+            );
+        });
+
+    Ok(())
 }
 
 fn main() {
@@ -38,9 +54,7 @@ fn main() {
             Err(err) => {
                 eprintln!("Could not process file {}:\n  {}", FILENAME, err);
             }
-            Ok(n) => {
-                println!("{}", n);
-            }
+            Ok(_n) => {}
         },
         Err(err) => {
             eprintln!("Error opening file {}:\n  {}", FILENAME, err);