day10: Add part 1 solution

day10/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "day10"
+version = "0.1.0"

day10/Cargo.toml

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

day10/src/main.rs

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+use std::error;
+use std::fs::File;
+use std::io::BufRead;
+use std::io::BufReader;
+
+const DEBUG: bool = false;
+
+fn main() -> Result<(), Box<dyn error::Error>> {
+	let f = File::open("input.txt")?;
+	let reader = BufReader::new(f);
+
+	let mut strength_sum = 0;
+	let mut strength = 1;
+	let mut cycle = 1;
+	for line in reader.lines() {
+		let line = line?;
+		let mut split_iter = line.split_whitespace();
+		let cmd = split_iter.next().ok_or("asdf")?;
+		match cmd {
+			"noop" => {
+				cycle += 1;
+				if (cycle % 40) == 20 {
+					strength_sum += strength * cycle;
+					if DEBUG {
+						println!("{} {} {}", cycle, strength, strength * cycle)
+					}
+				}
+			},
+			"addx" => {
+				cycle += 1;
+				if (cycle % 40) == 20 {
+					strength_sum += strength * cycle;
+					if DEBUG {
+						println!("{} {} {}", cycle, strength, strength * cycle)
+					}
+				}
+				cycle += 1;
+				let num: i32 = split_iter.next().ok_or("bla")?.parse()?;
+				strength += num;
+				if (cycle % 40) == 20 {
+					strength_sum += strength * cycle;
+					if DEBUG {
+						println!("{} {} {}", cycle, strength, strength * cycle)
+					}
+				}
+			},
+			_ => Err(format!("Unknown command: {}", cmd))?
+		};
+	}
+
+    println!("Signal strength is {}", strength_sum);
+    Ok(())
+}