Rust
Pt1 easy, pt2 cry
edit: Updated with more iterring :)
view code
#[test]
fn test_y2025_day6_part1() {
let input = include_str!("../../input/2025/day_6.txt");
let lines = input.lines().collect::<Vec<&str>>();
let nr = lines[0..4]
.iter()
.map(|l| {
l.split_whitespace()
.map(|s| s.parse::<usize>().unwrap())
.collect::<Vec<usize>>()
})
.collect::<Vec<Vec<usize>>>();
let operations = lines[4].split_whitespace().collect::<Vec<&str>>();
let total = operations
.iter()
.enumerate()
.map(|(i, op)| match *op {
"*" => [0, 1, 2, 3].iter().map(|j| nr[*j][i]).product::<usize>(),
"+" => [0, 1, 2, 3].iter().map(|j| nr[*j][i]).sum::<usize>(),
_ => panic!("Unknown operation {}", op),
})
.sum::<usize>();
assert_eq!(4412382293768, total);
println!("Total: {}", total);
}
#[test]
fn test_y2025_day6_part2() {
let input = std::fs::read_to_string("input/2025/day_6.txt").unwrap();
let lines = input
.lines()
.map(|s| s.chars().collect::<Vec<char>>())
.collect::<Vec<Vec<char>>>();
let mut i = lines[0].len();
let mut numbers = vec![];
let mut total = 0;
while i > 0 {
i -= 1;
let number = [0, 1, 2, 3]
.iter()
.filter_map(|j| lines[*j][i].to_digit(10))
.fold(0, |acc, x| acc * 10 + x);
if number == 0 {
continue;
}
numbers.push(number as usize);
match lines[4][i] {
'*' => {
total += numbers.iter().product::<usize>();
numbers.clear();
}
'+' => {
total += numbers.iter().sum::<usize>();
numbers.clear();
}
' ' => {}
_ => panic!("Unknown operation {}", lines[4][i]),
}
}
assert_eq!(7858808482092, total);
println!("Total: {}", total);
}