day 10

Simple challenge for today. Misread the instructions a few times but
implementing it wasn't too bad.

day_10/src/main.rs

@@ -1,3 +1,74 @@
+use std::{collections::HashSet, fs::read_to_string};
+
+const PATH: &str = "src/input";
+
 fn main() {
-    println!("Hello, world!");
+    let binding = read_to_string(PATH).expect("Error reading file");
+    assert!(binding.is_ascii());
+    let data = binding.trim().split('\n').into_iter();
+
+    // SCREEN OUTPUT
+    let mut vga = HashSet::<(i32, i32)>::new();
+
+    // REGISTERS
+    let mut rx = 1;
+    let mut ra = 0; // SIGNAL STRENGTH SUM
+    let mut rclk = 0;
+
+    macro_rules! update_clk {
+        () => {
+            // OUTPUT TO SCREEN
+            // CHECK ALL 3 POSITIONS OF SPRITE.
+            for dx in -1..=1 {
+                if rclk % 40 == rx + dx {
+                    vga.insert((rx + dx, rclk / 40));
+                }
+            }
+
+            // INCREMENT CLOCK
+            rclk += 1;
+
+            // UPDATE VOLTAGE COUNTER REGISTER
+            if (rclk - 20) % 40 == 0 {
+                ra += rclk * rx;
+            }
+        };
+    }
+
+    for instruction in data {
+        let mut tokens = instruction.split(' ');
+        // MATCH MNENOMIC AND UPDATE CLOCK
+        let mnenomic = tokens.next().unwrap();
+        match mnenomic {
+            "addx" => {
+                let operand = tokens.next().unwrap().parse::<i32>().unwrap();
+
+                // TWO CYCLES
+                update_clk!();
+                update_clk!();
+                rx += operand;
+            }
+            "noop" | _ => {
+                // ONE CYCLE
+                update_clk!();
+            }
+        }
+    }
+
+    println!("PART 1 {}", ra);
+    println!("PART 2");
+    print_screen(vga);
+}
+
+fn print_screen(vga: HashSet<(i32, i32)>) {
+    for j in 0..6 {
+        for i in 0..40 {
+            if vga.contains(&(i, j)) {
+                print!("#");
+            } else {
+                print!(".");
+            }
+        }
+        println!();
+    }
 }