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