day 7 part 1

src/day07.rs

@@ -0,0 +1,94 @@
+use std::fs::read_to_string;
+
+use itertools::Itertools;
+use regex::Regex;
+
+pub fn day_main() {
+    let input = read_to_string("input/day07.txt").unwrap();
+    let input = input.trim();
+    println!(" part1: {}", part1(input));
+    println!(" part2: {}", part2(input));
+}
+
+type RiddleResult = i64;
+
+fn part1(input: &str) -> RiddleResult {
+    let regex = Regex::new("(\\d+)").unwrap();
+    input
+        .lines()
+        .map(|line| {
+            regex
+                .find_iter(line)
+                .map(|capture| capture.as_str().parse::<i64>().unwrap())
+                .collect_vec()
+        })
+        .filter(well_calibrated)
+        .map(|v| v[0])
+        .sum()
+}
+
+fn well_calibrated(list: &Vec<i64>) -> bool {
+    let expected = list[0];
+    let operands = list.iter().skip(1).copied().collect_vec();
+    let operators = ops(operands.len() - 1);
+    for ops in operators.into_iter() {
+        // dbg!(&ops);
+        let v = ops
+            .into_iter()
+            .zip(operands.iter().skip(1))
+            .fold(operands[0], |acc, (op, val)| match op {
+                '*' => acc * val,
+                '+' => acc + val,
+                _ => panic!(),
+            });
+        if v == expected {
+            return true;
+        }
+    }
+    false
+}
+
+fn ops(n: usize) -> Vec<Vec<char>> {
+    if n == 1 {
+        return vec![vec!['+'], vec!['*']];
+    }
+    let v = ops(n - 1);
+    v.into_iter()
+        .flat_map(|vector| {
+            let mut v1 = vector.clone();
+            let mut v2 = vector;
+            v1.push('+');
+            v2.push('*');
+            [v1, v2]
+        })
+        .collect_vec()
+}
+
+fn part2(_input: &str) -> RiddleResult {
+    0
+}
+
+#[cfg(test)]
+mod test {
+    use super::{part1, part2};
+
+    const TEST_INPUT: &str = r"190: 10 19
+3267: 81 40 27
+83: 17 5
+156: 15 6
+7290: 6 8 6 15
+161011: 16 10 13
+192: 17 8 14
+21037: 9 7 18 13
+292: 11 6 16 20";
+
+    #[test]
+    fn test1() {
+        assert_eq!(part1(TEST_INPUT), 3749);
+    }
+
+    #[test]
+    fn test2() {
+        assert_eq!(part2(TEST_INPUT), 0);
+    }
+}

src/lib.rs

@@ -4,4 +4,5 @@ pub mod day03;
 pub mod day04;
 pub mod day05;
 pub mod day06;
+pub mod day07;
 pub mod utils;

src/main.rs

@@ -11,6 +11,7 @@ fn main() {
         (4, day04::day_main),
         (5, day05::day_main),
         (6, day06::day_main),
+        (7, day07::day_main),
     ]);
     let day: Option<u8> = args().nth(1).and_then(|a| a.parse().ok());
     let Some(day) = day else {