Add day one

2023/1/1/.gitignore

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+/target

2023/1/1/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"

2023/1/1/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]

2023/1/1/src/main.rs

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+fn main() {
+    let input = std::fs::read_to_string("./input").unwrap();
+
+    struct FirstLast {
+        first: Option<u32>,
+        last: Option<u32>,
+    }
+
+    impl FirstLast {
+        fn new() -> Self {
+            Self {
+                first: None,
+                last: None,
+            }
+        }
+
+        fn record(&mut self, n: u32) {
+            if self.first.is_none() {
+                self.first = Some(n)
+            } else {
+                self.last = Some(n)
+            }
+        }
+
+        fn value(self) -> u32 {
+            self.first.unwrap() * 10 + self.last.unwrap_or(self.first.unwrap())
+        }
+    }
+
+    let out: u32 = input
+        .lines()
+        .map(|line| {
+            line.chars().fold(FirstLast::new(), |mut val, char| {
+                if let Some(digit) = char.to_digit(10) {
+                    val.record(digit)
+                }
+                val
+            })
+        })
+        .map(FirstLast::value)
+        .sum();
+
+    println!("{:?}", out);
+}

2023/1/2/.gitignore

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+/target

2023/1/2/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"

2023/1/2/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]

2023/1/2/src/main.rs

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+fn main() {
+    let input = std::fs::read_to_string("./input").unwrap();
+
+    #[derive(Debug)]
+    struct FirstLast {
+        first: Option<u32>,
+        last: Option<u32>,
+    }
+
+    impl FirstLast {
+        fn new() -> Self {
+            Self {
+                first: None,
+                last: None,
+            }
+        }
+
+        fn record(&mut self, n: u32) {
+            if self.first.is_none() {
+                self.first = Some(n)
+            } else {
+                self.last = Some(n)
+            }
+        }
+
+        fn value(self) -> u32 {
+            self.first.unwrap() * 10 + self.last.unwrap_or(self.first.unwrap())
+        }
+    }
+
+    struct SpelledOutNumber(u32);
+
+    impl SpelledOutNumber {
+        fn parse(value: &str) -> Option<Self> {
+            if value.starts_with("one") {
+                Some(Self(1))
+            } else if value.starts_with("two") {
+                Some(Self(2))
+            } else if value.starts_with("three") {
+                Some(Self(3))
+            } else if value.starts_with("four") {
+                Some(Self(4))
+            } else if value.starts_with("five") {
+                Some(Self(5))
+            } else if value.starts_with("six") {
+                Some(Self(6))
+            } else if value.starts_with("seven") {
+                Some(Self(7))
+            } else if value.starts_with("eight") {
+                Some(Self(8))
+            } else if value.starts_with("nine") {
+                Some(Self(9))
+            } else {
+                None
+            }
+        }
+    }
+
+    let out: u32 = input
+        .lines()
+        .map(|line| {
+            let line: Vec<char> = line.chars().collect();
+            let mut recorder = FirstLast::new();
+            for i in 0..line.len() {
+                let c = &line[i];
+                if let Some(digit) = c.to_digit(10) {
+                    recorder.record(digit)
+                } else {
+                    let rest = &line[i..].iter().collect::<String>();
+                    if let Some(digit) = SpelledOutNumber::parse(rest.as_str()) {
+                        recorder.record(digit.0)
+                    }
+                }
+            }
+            recorder
+        })
+        .map(FirstLast::value)
+        .sum();
+
+    println!("{out}");
+}