Day 1 initial solutions

1/.gitignore

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+/target

1/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "day1"
+version = "0.1.0"

1/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]

1/src/main.rs

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+use std::fs::File;
+use std::io::{BufRead, BufReader, Lines};
+
+// BOILERPLATE
+type InputIter = Lines<BufReader<File>>;
+
+fn get_input() -> InputIter {
+    let f = File::open("input").unwrap();
+    let br = BufReader::new(f);
+    br.lines()
+}
+
+fn main() {
+    println!("Problem 1 solution: {}", problem1(get_input()));
+    println!("Problem 2 solution: {}", problem2(get_input()));
+}
+
+// PROBLEM1 solution
+fn problem1_lineval(line: &String) -> u64 {
+    // forward iterate to find the first numeric value
+    let first = line.chars().find(|c| c.is_digit(10)).unwrap();
+    let last = line.chars().rev().find(|c| c.is_digit(10)).unwrap();
+
+    (first.to_digit(10).unwrap() * 10 + last.to_digit(10).unwrap()).into()
+}
+
+fn problem1(input: InputIter) -> u64 {
+    input.map(|line| problem1_lineval(&line.unwrap())).sum()
+}
+
+// PROBLEM2 solution
+const DIGITS: &[(&str, u64)] = &[
+    ("one", 1),
+    ("two", 2),
+    ("three", 3),
+    ("four", 4),
+    ("five", 5),
+    ("six", 6),
+    ("seven", 7),
+    ("eight", 8),
+    ("nine", 9),
+];
+
+fn problem2_numeric(start: &str) -> Option<u64> {
+    let char = start.chars().nth(0).unwrap();
+    if char.is_numeric() {
+        Some(char.to_digit(10).unwrap().into())
+    } else {
+        for (s, n) in DIGITS {
+            if start.starts_with(s) {
+                return Some(*n);
+            }
+        }
+        None
+    }
+}
+
+fn problem2_lineval(line: &String) -> u64 {
+    let mut first = None;
+    for pos in 0..line.len() {
+        let (_, sub) = line.split_at(pos);
+        if let Some(n) = problem2_numeric(sub) {
+            first = Some(n);
+            break;
+        } else {
+            continue;
+        }
+    }
+    let mut second = None;
+    for pos in (0..line.len()).rev() {
+        let (_, sub) = line.split_at(pos);
+        if let Some(n) = problem2_numeric(sub) {
+            second = Some(n);
+            break;
+        } else {
+            continue;
+        }
+    }
+
+    first.unwrap() * 10 + second.unwrap()
+}
+
+fn problem2(input: InputIter) -> u64 {
+    input.map(|line| problem2_lineval(&line.unwrap())).sum()
+}