day1

2023/day1/src/main.rs

@@ -0,0 +1,47 @@
+use std::fs::File;
+use std::io::{self, BufRead};
+use std::path::Path;
+
+fn main() -> io::Result<()> {
+    // File must exist in the current path
+    let mut result = 0;
+    if let Ok(lines) = read_lines("./src/input") {
+        for line in lines.flatten() {
+            if let Some(value) = extract_digit_pair_sum(&line) {
+                println!("Current result: {} + {} = {}", result, value, result + value);
+                result += value;
+            }
+        }
+    }
+
+    println!("Final result: {}", result);
+    Ok(())
+}
+
+// Extracts first and last digits from a line, forms a number, and returns the sum
+fn extract_digit_pair_sum(line: &str) -> Option<i32> {
+    let first_digit = get_first_digit(line)?;
+    let last_digit = get_last_digit(line)?;
+    
+    let digit_str = format!("{}{}", first_digit, last_digit);
+    digit_str.parse::<i32>().ok()
+}
+
+// Helper function to get the first digit in the string
+fn get_first_digit(s: &str) -> Option<char> {
+    s.chars().find(|&c| c.is_digit(10))
+}
+
+// Helper function to get the last digit in the string
+fn get_last_digit(s: &str) -> Option<char> {
+    s.chars().rev().find(|&c| c.is_digit(10))
+}
+
+// Returns an Iterator over the lines in the file
+fn read_lines<P>(filename: P) -> io::Result<io::Lines<io::BufReader<File>>>
+where
+    P: AsRef<Path>,
+{
+    let file = File::open(filename)?;
+    Ok(io::BufReader::new(file).lines())
+}