From cb3a816c79786e847b74a7d28646e7b191f06efb Mon Sep 17 00:00:00 2001
From: Alpha Chen <alpha.chen@gmail.com>
Date: Sat, 8 Dec 2018 12:53:00 -0800
Subject: [PATCH] [2018][rust][05.2]

---
 2018/rust/src/bin/day_05.rs | 30 +++++++++++++++++++++++++-----
 1 file changed, 25 insertions(+), 5 deletions(-)

diff --git a/2018/rust/src/bin/day_05.rs b/2018/rust/src/bin/day_05.rs
index b0d0343..8953ebd 100644
--- a/2018/rust/src/bin/day_05.rs
+++ b/2018/rust/src/bin/day_05.rs
@@ -15,10 +15,27 @@ fn main() -> Result<(), Box<Error>> {
 }
 
 fn solve(input: &str) -> Result<String, Box<Error>> {
-    let reaction = Reaction {
-        polymer: input.trim().into(),
-    };
-    Ok(reaction.last().map(|x| x.len().to_string()).unwrap())
+    let polymer = input.trim();
+
+    // Part One
+    // let reaction = Reaction {
+    //     polymer: polymer.into()
+    // };
+    // Ok(reaction.last().map(|x| x.len().to_string()).unwrap())
+
+    // Part Two
+    let output = (b'a'..=b'z')
+        .map(|x| x as char)
+        .map(|x| {
+            polymer
+                .replace(x, "")
+                .replace(&x.to_uppercase().to_string(), "")
+        })
+        .map(|polymer| Reaction { polymer })
+        .flat_map(|reaction| reaction.last())
+        .map(|polymer| polymer.len())
+        .min();
+    Ok(output.unwrap().to_string())
 }
 
 #[test]
@@ -28,7 +45,10 @@ fn test_solve() {
     let output = solve(input).unwrap();
 
     // Part One
-    assert_eq!(output, "10".to_string());
+    // assert_eq!(output, "10".to_string());
+
+    // Part Two
+    assert_eq!(output, "4".to_string());
 }
 
 struct Reaction {