2017/10-11

2017/10/Cargo.lock

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+[[package]]
+name = "day-10"
+version = "0.1.0"
+

2017/10/Cargo.toml

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+[package]
+name = "day-10"
+version = "0.1.0"
+authors = ["logaritmisk <anders.e.olsson@gmail.com>"]
+
+[dependencies]

2017/10/input.txt

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+225,171,131,2,35,5,0,13,1,246,54,97,255,98,254,110

2017/10/src/main.rs

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+use std::io::{self, Read};
+
+
+fn hash(input: &[usize], list: &mut [usize], rounds: usize) {
+    let len = list.len();
+
+    let mut index = 0;
+    let mut skip = 0;
+
+    for _ in 0..rounds {
+        for x in input {
+            if *x > 0 {
+                let mut start = index;
+                let mut end = (index + *x - 1) % len;
+
+                for _ in 0..(*x / 2) {
+                    list.swap(start, end);
+
+                    start = if start == len - 1 { 0 } else { start + 1 };
+                    end = if end == 0 { len - 1 } else { end - 1 };
+                }
+            }
+
+            index = (index + *x + skip) % len;
+            skip += 1;
+        }
+    }
+}
+
+
+fn main() {
+    let mut input = String::new();
+
+    io::stdin()
+        .read_to_string(&mut input)
+        .expect("faild to read input");
+
+    for line in input.lines().filter(|line| !line.is_empty()) {
+        let input = line.split(',')
+            .filter_map(|num| num.parse::<usize>().ok())
+            .collect::<Vec<_>>();
+
+        let mut list = (0..256).collect::<Vec<_>>();
+
+        hash(&input, &mut list, 1);
+
+        println!("part_one={}", list[0] * list[1]);
+
+        let input = line.bytes()
+            .chain([17, 31, 73, 47, 23].iter().cloned())
+            .map(usize::from)
+            .collect::<Vec<_>>();
+
+        let mut list = (0..256).collect::<Vec<_>>();
+
+        hash(&input, &mut list, 64);
+
+        let hex = list.chunks(16)
+            .map(|chunk| chunk.iter().fold(0, |a, b| a ^ b))
+            .map(|block| format!("{:02x}", block))
+            .collect::<String>();
+
+        println!("part_two={}", hex);
+    }
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+
+    #[test]
+    fn test_hash() {
+        let mut list = [0, 1, 2, 3, 4];
+
+        hash(&[3, 4, 1, 5], &mut list, 1);
+
+        assert_eq!(list, [3, 4, 2, 1, 0]);
+    }
+}