Day 12 part 1.

Cargo.lock

@@ -8,6 +8,16 @@ version = "0.1.0"
 dependencies = [
  "aoc-runner",
  "aoc-runner-derive",
+ "regex",
+]
+
+[[package]]
+name = "aho-corasick"
+version = "1.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b2969dcb958b36655471fc61f7e416fa76033bdd4bfed0678d8fee1e2d07a1f0"
+dependencies = [
+ "memchr",
 ]
 
 [[package]]
@@ -45,6 +55,12 @@ version = "0.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1306f3464951f30e30d12373d31c79fbd52d236e5e896fd92f96ec7babbbe60b"
 
+[[package]]
+name = "memchr"
+version = "2.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "523dc4f511e55ab87b694dc30d0f820d60906ef06413f93d4d7a1385599cc149"
+
 [[package]]
 name = "proc-macro2"
 version = "0.4.21"
@@ -81,6 +97,35 @@ dependencies = [
  "proc-macro2 1.0.47",
 ]
 
+[[package]]
+name = "regex"
+version = "1.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "380b951a9c5e80ddfd6136919eef32310721aa4aacd4889a8d39124b026ab343"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-automata",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-automata"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5f804c7828047e88b2d32e2d7fe5a105da8ee3264f01902f796c8e067dc2483f"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c08c74e62047bb2de4ff487b251e4a92e24f48745648451635cec7d591162d9f"
+
 [[package]]
 name = "ryu"
 version = "0.2.7"

Cargo.toml

@@ -10,3 +10,4 @@ bench = false
 [dependencies]
 aoc-runner = "0.3.0"
 aoc-runner-derive = "0.3.0"
+regex = "1.10.2"

src/day12.rs

@@ -0,0 +1,24 @@
+use aoc_runner_derive::aoc;
+use regex::Regex;
+
+#[aoc(day12, part1)]
+fn part1(input: &str) -> i64 {
+    Regex::new(r"-?\d+")
+        .unwrap()
+        .find_iter(input)
+        .map(|m| m.as_str().parse::<i64>().unwrap())
+        .sum()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1("[1,2,3]"), 6);
+        assert_eq!(part1("{\"a\":2,\"b\":4}"), 6);
+        assert_eq!(part1(r"[[[3]]]"), 3);
+        assert_eq!(part1(r#"{"a":{"b":4},"c":-1}"#), 3);
+    }
+}

src/lib.rs

@@ -4,5 +4,6 @@ extern crate aoc_runner_derive;
 
 mod day10;
 mod day11;
+mod day12;
 
 aoc_lib! { year = 2015 }