diff options
Diffstat (limited to '2016/aoc14/src')
-rw-r--r-- | 2016/aoc14/src/main.rs | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/2016/aoc14/src/main.rs b/2016/aoc14/src/main.rs new file mode 100644 index 0000000..d9410ce --- /dev/null +++ b/2016/aoc14/src/main.rs @@ -0,0 +1,84 @@ +extern crate md5; + +use std::collections::HashMap; + +fn main() { +// let input = "abc"; + let input = "yjdafjpo"; + let mut index = 0; + let mut results_found = 0; + + let mut hash_memo = HashMap::new(); + while results_found < 64 { + let hash = stretched_hash(format!("{}{}", input, index), &mut hash_memo); + + let threes = find_concurrent_symbols(&hash, 3, true); + if threes.len() > 0 { +// println!("Found three at {} -> {}", index, hash); + for i in 1..1001 { + let hash = stretched_hash(format!("{}{}", input, index+i), &mut hash_memo); + let fives = find_concurrent_symbols(&hash, 5, false); + if fives.iter().any(|c| threes.contains(c)) { + results_found += 1; +// println!("Five found at {} -> {}", index+i, hash); + println!("Found hash {} at index {}", results_found, index); + break; + } + } + } + index += 1; + } + +} + +fn find_concurrent_symbols(hash: &String, count: u8, exit_early: bool) -> Vec<char> { + let mut last_symbol = None; + let mut last_symbol_run = 0; + let mut matches = Vec::new(); + for c in hash.chars() { + let symbol_matches = match last_symbol { + Some(s) => s == c, + None => false + }; + + if symbol_matches { + last_symbol_run += 1; + if last_symbol_run >= count && !matches.contains(&c) { + matches.push(c); + if exit_early { + break; + } + } + } else { + last_symbol = Some(c); + last_symbol_run = 1; + } + } + + matches +} + +fn hash_to_string(hash: &[u8; 16]) -> String { + let mut result = String::with_capacity(32); + + for &byte in hash.iter() { + result.push_str(format!("{:02x}", byte).as_ref()); + } + result +} + +fn stretched_hash(input: String, memo: &mut HashMap<String, String>) -> String { + memo.entry(input.clone()).or_insert_with(|| { + let mut result = input; + for _ in 0..2017 { + result = string_hash(result); + } + result + }).clone() +} + +fn string_hash(input: String) -> String { + let bytes_to_hash = input.into_bytes(); + let hash = md5::compute(bytes_to_hash.as_slice()); + hash_to_string(&hash) +} |