adventofcode

commit

bce59773e45df8012ff7ed4fd588f1c1214dfa07

parent

f31c202b7a601a53f261ded29cc0e4b4d88dcc90

Author

Tobias Bengfort <tobias.bengfort@posteo.de>

Date

2024-12-12 18:59

2024-12-11

Diffstat

3 files changed, 71 insertions, 0 deletions

diff --git a/2024/11/input.txt b/2024/11/input.txt

@@ -0,0 +1 @@
   -1     1 5 62914 65 972 0 805922 6521 1639064

diff --git a/2024/11/solution.rs b/2024/11/solution.rs

@@ -0,0 +1,69 @@
   -1     1 use std::collections::HashMap;
   -1     2 
   -1     3 #[path = "../lib.rs"]
   -1     4 mod lib;
   -1     5 
   -1     6 fn parse_input() -> Vec<u64> {
   -1     7     let line = lib::iter_input().next().unwrap();
   -1     8     return line.split(' ').map(|s| s.parse::<u64>().unwrap()).collect();
   -1     9 }
   -1    10 
   -1    11 fn count_digits(value: u64) -> usize {
   -1    12     let mut count = 0;
   -1    13     let mut v = value;
   -1    14     while v > 0 {
   -1    15         v /= 10;
   -1    16         count += 1;
   -1    17     }
   -1    18     return count;
   -1    19 }
   -1    20 
   -1    21 fn pow(base: u64, exp: usize) -> u64 {
   -1    22     if exp == 1 {
   -1    23         return base;
   -1    24     } else {
   -1    25         let p = pow(base, exp / 2);
   -1    26         if exp % 2 == 0 {
   -1    27             return p * p;
   -1    28         } else {
   -1    29             return p * p * base;
   -1    30         }
   -1    31     }
   -1    32 }
   -1    33 
   -1    34 fn next(value: u64, blinks: usize, cache: &mut HashMap<(u64, usize), usize>) -> usize {
   -1    35     let solution;
   -1    36     if blinks == 0 {
   -1    37         return 1;
   -1    38     } else if let Some(s) = cache.get(&(value, blinks)) {
   -1    39         return *s;
   -1    40     } else if value == 0 {
   -1    41         solution = next(1, blinks - 1, cache);
   -1    42     } else {
   -1    43         let digits = count_digits(value);
   -1    44         if digits % 2 == 0 {
   -1    45             let k = pow(10, digits / 2);
   -1    46             solution = next(value / k, blinks - 1, cache) + next(value % k, blinks - 1, cache);
   -1    47         } else {
   -1    48             solution = next(value * 2024, blinks - 1, cache);
   -1    49         }
   -1    50     }
   -1    51 
   -1    52     cache.insert((value, blinks), solution);
   -1    53     return solution;
   -1    54 }
   -1    55 
   -1    56 fn main() {
   -1    57     let values = parse_input();
   -1    58     let mut sum1 = 0;
   -1    59     let mut sum2 = 0;
   -1    60     let mut cache = HashMap::new();
   -1    61 
   -1    62     for value in values.iter() {
   -1    63         sum1 += next(*value, 25, &mut cache);
   -1    64         sum2 += next(*value, 75, &mut cache);
   -1    65     }
   -1    66 
   -1    67     println!("part1: {}", sum1);
   -1    68     println!("part2: {}", sum2);
   -1    69 }

diff --git a/2024/11/test.txt b/2024/11/test.txt

@@ -0,0 +1 @@
   -1     1 125 17