init project, add day 1

Cargo.toml

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+[package]
+name = "day_1-2"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+regex = "1.10.2"

src/main.rs

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+use regex::Regex;
+
+const WORDS: [&str; 19] = [
+    "one",
+    "two",
+    "three",
+    "four",
+    "five",
+    "six",
+    "seven",
+    "eight",
+    "nine",
+    "1", "2", "3", "4", "5",
+    "6", "7", "8", "9", "0",
+];
+
+fn main() {
+    let regex = Regex::new(WORDS.join("|").as_str()).unwrap();
+    let input = include_str!("../input.txt");
+    let mut results: Vec<i32> = Vec::new();
+
+    for line in input
+        .split("\n")
+        .filter(|line| !line.is_empty()
+    ) {
+        let mut numbers: Vec<char> = Vec::new();
+        let mut index: i32 = 0;
+
+        while let Some(m) = regex.find_at(&line, index as usize) {
+            index = m.start() as i32 + 1;
+            numbers.push(match m.as_str() {
+                "one" => '1',
+                "two" => '2',
+                "three" => '3',
+                "four" => '4',
+                "five" => '5',
+                "six" => '6',
+                "seven" => '7',
+                "eight" => '8',
+                "nine" => '9',
+                x => x.chars().next().unwrap()
+            });
+        }
+
+        let num: i32 = format!("{}{}", numbers.first().unwrap(), numbers.last().unwrap())
+            .parse()
+            .unwrap();
+        results.push(num);
+    }
+
+    println!("Result: {}", results.iter().sum::<i32>());
+}