Day 7

src/day6.rs

@@ -83,6 +83,7 @@ fn get_visited(board: &[Vec<Position>], mut pos: (usize, usize)) -> HashSet<(usi
     visited
 }
 
+#[allow(dead_code)]
 pub fn task1() {
     let (board, pos) = parse_board(&std::fs::read_to_string("input.txt").unwrap());
     let mut visited = get_visited(&board, pos);
@@ -109,6 +110,7 @@ fn is_loop(board: &[Vec<Position>], mut pos: (usize, usize)) -> bool {
     }
 }
 
+#[allow(dead_code)]
 pub fn task2() {
     let (mut board, pos) = parse_board(&std::fs::read_to_string("input.txt").unwrap());
     let visited = get_visited(&board, pos);

src/day7.rs

@@ -0,0 +1,58 @@
+use crate::get_lines;
+
+use itertools::Itertools;
+
+#[derive(Clone, Copy)]
+enum Operation {
+    Add,
+    Mul,
+    Concentration,
+}
+
+impl Operation {
+    fn apply(self, a: u64, b: u64) -> u64 {
+        match self {
+            Self::Add => a + b,
+            Self::Mul => a * b,
+            Self::Concentration => {
+                let val = format!("{a}{b}");
+                val.parse().unwrap()
+            }
+        }
+    }
+}
+
+fn inner(ops: &[Operation]) {
+    let lines = get_lines("input.txt");
+    let result: u64 = lines
+        .filter_map(|line| {
+            let (target, numbers) = line.split_once(": ").unwrap();
+            let target: u64 = target.parse().unwrap();
+            let numbers: Vec<u64> = numbers.split(' ').map(|num| num.parse().unwrap()).collect();
+            let ops_set = (0..numbers.len() - 1)
+                .map(|_| ops.iter().copied())
+                .multi_cartesian_product();
+            for ops in ops_set {
+                let mut result = numbers[0];
+                for (n, op) in numbers[1..].iter().zip(ops) {
+                    result = op.apply(result, *n);
+                }
+                if result == target {
+                    return Some(target);
+                }
+            }
+            None
+        })
+        .sum();
+    println!("{result}");
+}
+
+#[allow(dead_code)]
+pub fn task1() {
+    inner(&[Operation::Add, Operation::Mul]);
+}
+
+#[allow(dead_code)]
+pub fn task2() {
+    inner(&[Operation::Add, Operation::Mul, Operation::Concentration]);
+}

src/main.rs

@@ -4,6 +4,7 @@ mod day3;
 mod day4;
 mod day5;
 mod day6;
+mod day7;
 
 use std::{
     fs::File,
@@ -21,6 +22,6 @@ fn parse_line(line: &str, pattern: char) -> impl Iterator<Item = i32> + '_ {
 }
 
 fn main() {
-    day6::task1();
+    day7::task1();
-    day6::task2();
+    day7::task2();
 }