Solution for 2022/day10-part1

2022/day10-part1/Cargo.toml

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+[package]
+name = "day10-part1"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

2022/day10-part1/src/main.rs

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+fn main() {
+    // Use command line arguments to specify the input filename.
+    let args: Vec<String> = std::env::args().collect();
+    if args.len() < 2 {
+        panic!("Usage: ./main <input-file>\nNo input file provided. Exiting.");
+    }
+
+    // Next, read the contents of the input file into a string for easier processing.
+    let input = std::fs::read_to_string(&args[1]).expect("Error opening file");
+    // Line-by-line processing is easiest.
+    let input = input.lines();
+
+    // --- TASK BEGIN ---
+
+    // Keep track of the current value of X for all the instructions.
+    // We'll use one massive vector for that purpose.
+    let mut x_over_time: Vec<i32> = Vec::with_capacity(512);
+    
+    // Keep track of the actual x as well.
+    let mut x = 1;
+
+    // Then, process line-by-line.
+    for line in input {
+        // Split by space.
+        let line: Vec<_> = line.split(' ').collect();
+
+        // Differentiate by instruction
+        match line[0] {
+            "noop" => {
+                // Nothing changes.
+                x_over_time.push(x);
+            }
+            "addx" => {
+                // Addition is complete *after* two cycles.
+                // So during those two cycles x has the old value still.
+                x_over_time.push(x);
+                x_over_time.push(x);
+                // Of course, afterwards the value of x is updated.
+                x += line[1].parse::<i32>().unwrap();
+            }
+            _ => ()
+        }
+    }
+
+    // dbg!(&x_over_time);
+
+    // Afterwards, compute our signal strength result.
+    let mut signal_strength = 0;
+    for (i,x) in x_over_time.iter().skip(19).step_by(40).enumerate() {
+        let cycle: i32 = 20 + (i as i32) * 40;
+        signal_strength += cycle * x;
+    }
+
+    println!("Signal strength: {}", signal_strength);
+}
+