Puzzle 25 2022

2022/Cargo.toml

@@ -85,3 +85,6 @@ name = "puzzle_23"
 
 [[example]]
 name = "puzzle_24"
+
+[[example]]
+name = "puzzle_25"

2022/examples/puzzle_25/main.rs

@@ -0,0 +1,76 @@
+use std::{ops::Sub, time::Instant};
+
+fn parse(line: &str) -> i128 {
+    let mut line_sum = 0;
+    for (index, char) in line.chars().rev().enumerate() {
+        let exponent_term = 5i128.pow(index as u32);
+        match char {
+            '2' => line_sum += 2 * exponent_term,
+            '1' => line_sum += exponent_term,
+            '0' => continue,
+            '-' => line_sum = line_sum.sub(exponent_term),
+            '=' => line_sum = line_sum.sub(2 * exponent_term),
+            _ => continue,
+        };
+    }
+    line_sum
+}
+
+fn to_snafu(number: i128) -> String {
+    let mut snafu = String::from("");
+    let mut n = number.clone();
+    while n > 0 {
+        let modulus = n % 5;
+        n /= 5;
+        let char = match modulus {
+            0 => "0",
+            1 => "1",
+            2 => "2",
+            3 => "=",
+            4 => "-",
+            _ => panic!("Not this!"),
+        };
+        snafu.push_str(&char);
+        if modulus >= 3 {
+            n += 1;
+        }
+    }
+    snafu.chars().rev().collect::<String>()
+}
+
+fn puzzle(contents: &str) -> String {
+    let mut answer = 0;
+    for line in contents.lines() {
+        answer += parse(line);
+    }
+    to_snafu(answer)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use rstest::*;
+
+    #[rstest]
+    #[case("1121-1110-1=0", 314159265)]
+    #[case("1-0---0", 12345)]
+    fn test_(#[case] input: &str, #[case] expected: i128) {
+        assert_eq!(parse(input), expected);
+    }
+
+    #[rstest]
+    #[case(314159265, "1121-1110-1=0")]
+    #[case(12345, "1-0---0")]
+    fn test_to_snafu(#[case] input: i128, #[case] expected: String) {
+        assert_eq!(to_snafu(input), expected);
+    }
+}
+
+fn main() {
+    let start = Instant::now();
+    let contents = include_str!("./input.txt");
+    let answer = puzzle(contents);
+    println!("Answer is: {}", answer);
+    let duration = start.elapsed();
+    println!("Took {:?} to solve this puzzle", duration);
+}