day05 performance push part 2 through more efficient case insensitive comparison

Cargo.lock

@@ -11,6 +11,7 @@ name = "aoc_2018"
 version = "0.1.0"
 dependencies = [
  "chrono 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "itertools 0.7.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -29,6 +30,19 @@ dependencies = [
  "time 0.1.40 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "either"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "itertools"
+version = "0.7.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "either 1.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "lazy_static"
 version = "1.2.0"
@@ -143,6 +157,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum aho-corasick 0.6.9 (registry+https://github.com/rust-lang/crates.io-index)" = "1e9a933f4e58658d7b12defcf96dc5c720f20832deebe3e0a19efd3b6aaeeb9e"
 "checksum cfg-if 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "082bb9b28e00d3c9d39cc03e64ce4cea0f1bb9b3fde493f0cbc008472d22bdf4"
 "checksum chrono 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)" = "45912881121cb26fad7c38c17ba7daa18764771836b34fab7d3fbd93ed633878"
+"checksum either 1.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3be565ca5c557d7f59e7cfcf1844f9e3033650c929c6566f511e8005f205c1d0"
+"checksum itertools 0.7.11 (registry+https://github.com/rust-lang/crates.io-index)" = "0d47946d458e94a1b7bcabbf6521ea7c037062c81f534615abcad76e84d4970d"
 "checksum lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "a374c89b9db55895453a74c1e38861d9deec0b01b405a82516e9d5de4820dea1"
 "checksum libc 0.2.44 (registry+https://github.com/rust-lang/crates.io-index)" = "10923947f84a519a45c8fefb7dd1b3e8c08747993381adee176d7a82b4195311"
 "checksum memchr 2.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "0a3eb002f0535929f1199681417029ebea04aadc0c7a4224b46be99c7f5d6a16"

Cargo.toml

@@ -6,3 +6,4 @@ authors = ["Johannes <jschaef@mail.uni-paderborn.de>"]
 [dependencies]
 regex = "1.1.0"
 chrono = "0.4.6"
+itertools = "0.7.11"

src/lib.rs

@@ -1,4 +1,5 @@
 extern crate chrono;
+extern crate itertools;
 extern crate regex;
 
 pub mod tasks;

src/main.rs

@@ -1,4 +1,4 @@
 fn main() {
-    // aoc_2018::tasks::day05::task1();
+    aoc_2018::tasks::day05::task1();
     aoc_2018::tasks::day05::task2();
 }

src/tasks/day05.rs

@@ -1,15 +1,19 @@
+use std::time::Instant;
 use utils;
 
 pub fn task1() {
     let mut input = utils::read_file("input/day05.txt");
+    let start = Instant::now();
     input = reduce(input.as_str());
 
-    println!("resulting polymer: {}", input);
+    println!("Duration: {:?}", Instant::now() - start);
     println!("RESULT: {}", input.len());
 }
 
 pub fn task2() {
     let input = utils::read_file("input/day05.txt");
+    let start = Instant::now();
+    let input = reduce(&input);
     let best = "abcdefghijklmnopqrstuvwxyz"
         .chars()
         .map(|c| {
@@ -18,13 +22,14 @@ pub fn task2() {
                 reduce(
                     &input
                         .chars()
-                        .filter(|ch| ch.to_lowercase().next().unwrap() != c)
+                        .filter(|ch| ch.eq_ignore_ascii_case(&c))
                         .collect::<String>(),
                 ).len(),
             )
         }).min_by_key(|it| it.1)
         .unwrap();
 
+    println!("Duration: {:?}", Instant::now() - start);
     println!("Best: {} (length {})", best.0, best.1);
 }
 
@@ -42,13 +47,7 @@ fn reduce(input: &str) -> String {
             }
 
             if let Some(last) = last {
-                if c.is_lowercase()
+                if c.eq_ignore_ascii_case(&last) && c != last {
-                    && last.is_uppercase()
-                    && c == last.to_lowercase().next().unwrap()
-                    || last.is_lowercase()
-                        && c.is_uppercase()
-                        && last == c.to_lowercase().next().unwrap()
-                {
                     stack.pop();
                 } else {
                     stack.push(c);