solution: day25 part1

src/bin/25.rs

@@ -0,0 +1,40 @@
+const ONE: u64 = 20151125;
+pub fn part_one(input: &str) -> Option<u64> {
+    let l = input.len();
+    let (row, column): (u32, u32) = input[80..l - 1]
+        .split_once(", column ")
+        .map(|(x, y)| (x.parse().unwrap(), y.parse().unwrap()))
+        .unwrap();
+
+    let n = (row + column) * (row + column - 1) / 2 - row + 1;
+    let mut c = 1;
+    let mut code = ONE;
+    while c < n {
+        code = (code * 252533) % 33554393;
+        c += 1;
+    }
+
+    Some(code)
+}
+pub fn part_two(input: &str) -> Option<u32> {
+    None
+}
+fn main() {
+    let input = &aoc::read_file("inputs", 25);
+    aoc::solve!(1, part_one, input);
+    aoc::solve!(2, part_two, input);
+}
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        let input = aoc::read_file("test_inputs", 25);
+        assert_eq!(part_one(&input.trim()), Some(7726640));
+    }
+    #[test]
+    fn test_part_two() {
+        let input = aoc::read_file("test_inputs", 25);
+        assert_eq!(part_two(&input.trim()), None);
+    }
+}

src/test_inputs/25.txt

@@ -0,0 +1 @@
+To continue, please consult the code grid in the manual.  Enter the code at row 2, column 4.