Day 7

Author: prevostc

Cargo.lock

@@ -20,6 +20,7 @@ today = ["chrono"]
 test_lib = []
 
 [dependencies]
+bit-set = "0.8.0"
 
 # Template dependencies
 chrono = { version = "0.4.38", optional = true }

Cargo.toml

@@ -0,0 +1,9 @@
+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

data/examples/07.txt

@@ -0,0 +1,112 @@
+advent_of_code::solution!(7);
+use itertools::Itertools;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum Op {
+    Add,
+    Mul,
+    Concat,
+}
+
+type OpVec = Vec<Op>;
+#[derive(Debug)]
+struct EquationData {
+    test_value: u64,
+    values: Vec<u64>,
+}
+
+impl EquationData {
+    fn parse(line: &str) -> Self {
+        let (left, right) = line.split_once(": ").unwrap();
+        let test_value = left.parse().unwrap();
+        let values = right.split(" ").map(|s| s.parse().unwrap()).collect();
+        Self { test_value, values }
+    }
+
+    fn eval(&self, ops: &OpVec) -> u64 {
+        let mut res = 0;
+        let mut op = Op::Add;
+        for i in 0..self.values.len() {
+            let v = self.values[i];
+            res = match op {
+                Op::Add => res + v,
+                Op::Mul => res * v,
+                Op::Concat => {
+                    let char_count = v.to_string().len() as u32;
+                    res * 10_u64.pow(char_count) + v
+                }
+            };
+            if i < ops.len() {
+                op = ops[i];
+            }
+        }
+        res
+    }
+}
+
+pub fn part_one(input: &str) -> Option<u64> {
+    const ALL_OPS: [Op; 2] = [Op::Add, Op::Mul];
+    let sum = input
+        .lines()
+        .filter(|l| !l.is_empty())
+        .map(|l| EquationData::parse(l))
+        .filter(|eq| {
+            for ops in std::iter::repeat_n(ALL_OPS, eq.values.len() - 1).multi_cartesian_product() {
+                if eq.eval(&ops) == eq.test_value {
+                    return true;
+                }
+            }
+            false
+        })
+        .map(|eq| eq.test_value)
+        .sum();
+    Some(sum)
+}
+
+pub fn part_two(input: &str) -> Option<u64> {
+    const ALL_OPS: [Op; 3] = [Op::Add, Op::Mul, Op::Concat];
+    let sum = input
+        .lines()
+        .filter(|l| !l.is_empty())
+        .map(|l| EquationData::parse(l))
+        .filter(|eq| {
+            for ops in std::iter::repeat_n(ALL_OPS, eq.values.len() - 1).multi_cartesian_product() {
+                if eq.eval(&ops) == eq.test_value {
+                    return true;
+                }
+            }
+            false
+        })
+        .map(|eq| eq.test_value)
+        .sum();
+    Some(sum)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_eval() {
+        let eq = EquationData {
+            test_value: 10,
+            values: vec![1, 2, 3],
+        };
+        assert_eq!(eq.eval(&vec![Op::Add, Op::Add]), 6);
+        assert_eq!(eq.eval(&vec![Op::Add, Op::Mul]), 9);
+        assert_eq!(eq.eval(&vec![Op::Mul, Op::Add]), 5);
+        assert_eq!(eq.eval(&vec![Op::Mul, Op::Mul]), 6);
+    }
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(3749));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(11387));
+    }
+}