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author | June McEnroe <programble@gmail.com> | 2017-12-24 10:59:42 -0500 |
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committer | June McEnroe <programble@gmail.com> | 2017-12-24 10:59:42 -0500 |
commit | 074b1f40b038f9f2462168960210e2e2c150b986 (patch) | |
tree | 44326597ac9a43997b707018c9ed52088871def1 /2017 | |
parent | Day 14 (diff) | |
download | aoc-074b1f40b038f9f2462168960210e2e2c150b986.tar.gz aoc-074b1f40b038f9f2462168960210e2e2c150b986.zip |
Day 15
Diffstat (limited to '2017')
-rw-r--r-- | 2017/input/day15.txt | 2 | ||||
-rw-r--r-- | 2017/src/bin/day15.rs | 49 |
2 files changed, 51 insertions, 0 deletions
diff --git a/2017/input/day15.txt b/2017/input/day15.txt new file mode 100644 index 0000000..fdc2fa8 --- /dev/null +++ b/2017/input/day15.txt @@ -0,0 +1,2 @@ +Generator A starts with 883 +Generator B starts with 879 \ No newline at end of file diff --git a/2017/src/bin/day15.rs b/2017/src/bin/day15.rs new file mode 100644 index 0000000..dbf041a --- /dev/null +++ b/2017/src/bin/day15.rs @@ -0,0 +1,49 @@ +use std::io::{self, Read}; + +struct GenA(u64); + +impl Iterator for GenA { + type Item = u64; + + fn next(&mut self) -> Option<u64> { + self.0 = self.0.wrapping_mul(16807) % 2147483647; + Some(self.0) + } +} + +struct GenB(u64); + +impl Iterator for GenB { + type Item = u64; + + fn next(&mut self) -> Option<u64> { + self.0 = self.0.wrapping_mul(48271) % 2147483647; + Some(self.0) + } +} + +fn judge(a: u64, b: u64) -> usize { + GenA(a).zip(GenB(b)) + .take(40_000_000) + .filter(|&(a, b)| a & 0xFFFF == b & 0xFFFF) + .count() +} + +fn solve1(input: &str) -> usize { + let mut iter = input.split_whitespace(); + let a = iter.clone().nth(4).unwrap().parse().unwrap(); + let b = iter.nth(9).unwrap().parse().unwrap(); + judge(a, b) +} + +fn main() { + let mut input = String::new(); + io::stdin().read_to_string(&mut input).unwrap(); + + println!("Part 1: {}", solve1(input.trim())); +} + +#[test] +fn part1() { + assert_eq!(588, judge(65, 8921)); +} |