2017 day 5

Author: ictrobot

crates/year2017/src/day05.rs

@@ -0,0 +1,51 @@
+use utils::prelude::*;
+
+/// Counting steps through a maze of jump instructions.
+#[derive(Clone, Debug)]
+pub struct Day05 {
+    jumps: Vec<i32>,
+}
+
+impl Day05 {
+    pub fn new(input: &str, _: InputType) -> Result<Self, InputError> {
+        Ok(Self {
+            jumps: parser::i32().parse_lines(input)?,
+        })
+    }
+
+    #[must_use]
+    pub fn part1(&self) -> u64 {
+        let mut jumps = self.jumps.clone();
+        let mut steps = 0;
+        let mut pc = 0;
+
+        while pc < jumps.len() {
+            let offset = jumps[pc];
+            jumps[pc] += 1;
+            pc = pc.wrapping_add_signed(offset as isize);
+            steps += 1;
+        }
+
+        steps
+    }
+
+    #[must_use]
+    pub fn part2(&self) -> u64 {
+        let mut jumps = self.jumps.clone();
+        let mut steps = 0;
+        let mut pc = 0;
+
+        while pc < jumps.len() {
+            let offset = jumps[pc];
+            jumps[pc] += if offset >= 3 { -1 } else { 1 };
+            pc = pc.wrapping_add_signed(offset as isize);
+            steps += 1;
+        }
+
+        steps
+    }
+}
+
+examples!(Day05 -> (u64, u64) [
+    {input: "0\n3\n0\n1\n-3", part1: 5, part2: 10},
+]);

crates/year2017/src/lib.rs

@@ -6,4 +6,5 @@ utils::year!(2017 => year2017, ${
     2 => day02::Day02,
     3 => day03::Day03,
     4 => day04::Day04<'_>,
+    5 => day05::Day05,
 });