2017/13

2017/13/Cargo.lock

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+[[package]]
+name = "day-13"
+version = "0.1.0"
+

2017/13/Cargo.toml

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+[package]
+name = "day-13"
+version = "0.1.0"
+authors = ["Anders Olsson <anders.e.olsson@gmail.com>"]
+
+[dependencies]

2017/13/input.txt

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+0: 5
+1: 2
+2: 3
+4: 4
+6: 6
+8: 4
+10: 6
+12: 10
+14: 6
+16: 8
+18: 6
+20: 9
+22: 8
+24: 8
+26: 8
+28: 12
+30: 12
+32: 8
+34: 8
+36: 12
+38: 14
+40: 12
+42: 10
+44: 14
+46: 12
+48: 12
+50: 24
+52: 14
+54: 12
+56: 12
+58: 14
+60: 12
+62: 14
+64: 12
+66: 14
+68: 14
+72: 14
+74: 14
+80: 14
+82: 14
+86: 14
+90: 18
+92: 17

2017/13/src/main.rs

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+use std::io::{self, BufRead};
+
+#[derive(Debug)]
+struct Layer {
+    depth: usize,
+    range: usize,
+}
+
+impl Layer {
+    fn new(depth: usize, range: usize) -> Layer {
+        Layer { depth, range }
+    }
+
+    fn is_scanner_at(&self, delta: usize, index: usize) -> bool {
+        let time = self.depth + delta;
+        let c = (self.range - 1) * 2;
+
+        time % c == index || time % c == (c - index)
+    }
+
+    fn severity(&self) -> usize {
+        self.depth * self.range
+    }
+}
+
+fn main() {
+    let stdin = io::stdin();
+
+    let firewall = stdin
+        .lock()
+        .lines()
+        .filter_map(Result::ok)
+        .map(|line| {
+            let digits = line
+                .split(": ")
+                .map(|digit| digit.parse::<usize>().expect("failed to parse digit"))
+                .collect::<Vec<_>>();
+
+            Layer::new(digits[0], digits[1])
+        }).collect::<Vec<_>>();
+
+    let mut severity = 0;
+
+    for layer in &firewall {
+        if layer.is_scanner_at(0, 0) {
+            severity += layer.severity();
+        }
+    }
+
+    println!("part.one={}", severity);
+
+    let mut delta = 0;
+
+    'iteration: loop {
+        for layer in &firewall {
+            if layer.is_scanner_at(delta, 0) {
+                delta += 1;
+
+                continue 'iteration;
+            }
+        }
+
+        break;
+    }
+
+    println!("part.two={}", delta);
+}

2017/13/test.txt

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+0: 3
+1: 2
+4: 4
+6: 4