day 2 and revised day 1 with advantage of DoubleEndedIterator

src/bin/day1_revised.rs

@@ -0,0 +1,91 @@
+use aoc23::prelude::*;
+
+fn part1(input: String) -> Result<usize> {
+    let mut sum = 0;
+    for line in input.lines().into_iter() {
+        let chars = line.chars();
+        let first_num: usize = chars
+            .clone()
+            .into_iter()
+            .skip_while(|c| !c.is_digit(10))
+            .take(1)
+            // This would get continuous digits: .take_while(|c| c.is_digit(10))
+            .collect::<String>()
+            .parse()?;
+        let last_num: usize = chars
+            .into_iter()
+            .rev()
+            .skip_while(|c| !c.is_digit(10))
+            .take(1)
+            .collect::<String>()
+            .parse()?;
+        let value = first_num * 10 + last_num;
+        sum += value;
+    }
+
+    // println!("Answer: {}", sum);
+    Ok(sum)
+}
+
+fn part_2(input: String) -> Result<u32> {
+    let numbers: [(&'static str, u32); 9] = [
+        ("one", 1),
+        ("two", 2),
+        ("three", 3),
+        ("four", 4),
+        ("five", 5),
+        ("six", 6),
+        ("seven", 7),
+        ("eight", 8),
+        ("nine", 9),
+    ];
+    let mut sum = 0;
+    for line in input.lines().into_iter() {
+        let mut chars = line.chars();
+        let mut peek_index = 0;
+        let first_num = loop {
+            // I wanted this to work but peek advances the iterator anyways despite saying it
+            // doesn't. I don't understand
+            //
+            // ```
+            // if let Some(Some(peek_digit)) = chars.by_ref().peekable().peek().map(|c| c.to_digit(10))
+            // ```
+            if let Some(Some(peek_digit)) = line.chars().nth(peek_index).map(|c| c.to_digit(10)) {
+                break peek_digit;
+            }
+            if let Some((_, digit)) = numbers.iter().find(|num| chars.as_str().starts_with(num.0)) {
+                break *digit;
+            }
+            if chars.next().is_none() {
+                break 0;
+            }
+            peek_index += 1;
+        };
+        let last_num = loop {
+            if let Some((_, digit)) = numbers.iter().find(|num| chars.as_str().ends_with(num.0)) {
+                break *digit;
+            }
+            if let Some(last_char) = chars.next_back() {
+                if let Some(digit) = last_char.to_digit(10) {
+                    break digit;
+                }
+            } else {
+                break first_num;
+            }
+        };
+        let value = first_num * 10 + last_num;
+        sum += value;
+        println!("Line {line}: a:{first_num}|b:{last_num} = {value} ++ {sum}");
+    }
+    Ok(sum)
+}
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    println!("Day 1");
+    println!("=====");
+    let input = utils::aoc::get_puzzle_input(1).await?;
+    println!("part 1: {}", part1(input.clone())?);
+    println!("part 2: {}", part_2(input.clone())?);
+    Ok(())
+}