Add first half of first day's solution for 2023

2023/day1/Cargo.toml

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+[package]
+name = "day1"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

2023/day1/README.md

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+# Day 1: Trebuchet?!
+
+Something is wrong with global snow production, and you've been selected to take a look. 
+The Elves have even given you a map; on it, they've used stars to mark the top fifty 
+locations that are likely to be having problems.
+
+You've been doing this long enough to know that to restore snow operations, you need to 
+check all *fifty stars* by December 25th.
+
+Collect stars by solving puzzles. Two puzzles will be made available on each day in 
+the Advent calendar; the second puzzle is unlocked when you complete the first. Each 
+puzzle grants *one star*. Good luck!
+
+You try to ask why they can't just use a weather machine ("not powerful enough") and where 
+they're even sending you ("the sky") and why your map looks mostly blank ("you sure ask a 
+lot of questions") and hang on did you just say the sky ("of course, where do you think 
+snow comes from") when you realize that the Elves are already loading you into a 
+trebuchet ("please hold still, we need to strap you in").
+
+As they're making the final adjustments, they discover that their calibration 
+document (your puzzle input) has been **amended** by a very young Elf who was apparently 
+just excited to show off her art skills. Consequently, the Elves are having trouble 
+reading the values on the document.
+
+The newly-improved calibration document consists of lines of text; each line originally 
+contained a specific **calibration value** that the Elves now need to recover. On each line,
+the calibration value can be found by combining the **first digit** and the **last digit** 
+(in that order) to form a single **two-digit number**.
+
+For example:
+
+```
+1abc2
+pqr3stu8vwx
+a1b2c3d4e5f
+treb7uchet
+```
+
+In this example, the calibration values of these four lines are 12, 38, 15, and 77. 
+Adding these together produces 142.
+
+Consider your entire calibration document. **What is the sum of all of the calibration values?**

2023/day1/src/main.rs

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+use std::collections::VecDeque;
+
+fn get_lines(raw: &str) -> Vec<Vec<char>> {
+    raw.split('\n').map(|line| line.chars().collect()).collect()
+}
+
+fn filter_lines(raw: &Vec<Vec<char>>) -> Vec<VecDeque<char>> {
+    raw.iter()
+        .map(|line| {
+            let line: Vec<char> = line
+                .into_iter()
+                .filter(|c| c.is_digit(10))
+                .map(|c| c.to_owned())
+                .collect();
+            VecDeque::from(line)
+        })
+        .collect()
+}
+
+fn get_values(raw: &mut Vec<VecDeque<char>>) -> Vec<usize> {
+    raw.iter_mut()
+        .map(|line| {
+            let first = match line.pop_front() {
+                Some(c) => c,
+                None => '0',
+            };
+            let last = match line.pop_back() {
+                Some(c) => c,
+                None => first,
+            };
+            let str: String = Vec::from([first, last]).into_iter().collect();
+
+            return usize::from_str_radix(&str, 10).unwrap();
+        })
+        .collect()
+}
+
+fn sum(raw: Vec<usize>) -> usize {
+    raw.into_iter().reduce(|accum, item| accum + item).unwrap()
+}
+
+fn main() {
+    let file_str = include_str!("input.txt");
+    let lines = get_lines(file_str);
+    let mut lines = filter_lines(&lines);
+    let values = get_values(&mut lines);
+
+    println!("Total: {}", sum(values));
+}