Day 12 part 2.

src/day12.rs

@@ -1,4 +1,5 @@
 use aoc_runner_derive::aoc;
+use json::{parse, JsonValue};
 use regex::Regex;
 
 #[aoc(day12, part1)]
@@ -10,6 +11,32 @@ fn part1(input: &str) -> i64 {
         .sum()
 }
 
+#[aoc(day12, part2)]
+fn part2(input: &str) -> i64 {
+    let json = parse(input).unwrap();
+    sum(&json)
+}
+
+fn sum(json: &JsonValue) -> i64 {
+    match json {
+        JsonValue::Null => 0,
+        JsonValue::Short(_) => 0,
+        JsonValue::String(_) => 0,
+        JsonValue::Number(_) => json.as_i64().unwrap(),
+        JsonValue::Boolean(_) => 0,
+        JsonValue::Object(o) => {
+            if o.iter().any(|(_, value)| {
+                value.is_string() && Some("red") == value.as_str()
+            }) {
+                0
+            } else {
+                o.iter().map(|(_key, value)| sum(value)).sum()
+            }
+        }
+        JsonValue::Array(a) => a.iter().map(|e| sum(e)).sum(),
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;