65 lines
1.3 KiB
Rust
65 lines
1.3 KiB
Rust
|
use std::fs::File;
|
||
|
|
use std::io;
|
||
|
|
use std::io::prelude::*;
|
||
|
|
use std::path::Path;
|
||
|
|
|
||
|
|
fn parse_input<B: BufRead>(buf: B) -> Vec<u64> {
|
||
|
|
buf.lines()
|
||
|
|
.map(|line| {
|
||
|
|
line.expect("Failed to read line.")
|
||
|
|
.parse()
|
||
|
|
.expect("Failed to parse line input.")
|
||
|
|
})
|
||
|
|
.collect()
|
||
|
|
}
|
||
|
|
|
||
|
|
fn puzzle_a(nums: &[u64]) -> Option<u64> {
|
||
|
|
for a in nums {
|
||
|
|
for b in nums {
|
||
|
|
if a + b == 2020 {
|
||
|
|
return Some(a * b);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
None
|
||
|
|
}
|
||
|
|
|
||
|
|
fn puzzle_b(nums: &[u64]) -> Option<u64> {
|
||
|
|
for a in nums {
|
||
|
|
for b in nums {
|
||
|
|
for c in nums {
|
||
|
|
if a + b + c == 2020 {
|
||
|
|
return Some(a * b * c);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
None
|
||
|
|
}
|
||
|
|
|
||
|
|
fn open_file<P>(filename: P) -> io::Result<io::BufReader<File>>
|
||
|
|
where
|
||
|
|
P: AsRef<Path>,
|
||
|
|
{
|
||
|
|
let file = File::open(filename)?;
|
||
|
|
Ok(io::BufReader::new(file))
|
||
|
|
}
|
||
|
|
|
||
|
|
fn main() -> Result<(), &'static str> {
|
||
|
|
let buffer = open_file("input").unwrap();
|
||
|
|
let puzzle_input = parse_input(buffer);
|
||
|
|
|
||
|
|
println!(
|
||
|
|
"Part A:\n{}",
|
||
|
|
puzzle_a(&puzzle_input).expect("No solution for A found.")
|
||
|
|
);
|
||
|
|
println!("--------");
|
||
|
|
println!(
|
||
|
|
"Part B:\n{}",
|
||
|
|
puzzle_b(&puzzle_input).expect("No solution for B found.")
|
||
|
|
);
|
||
|
|
|
||
|
|
Ok(())
|
||
|
|
}
|