perf(08/2015): use str slice instead of iterator to compare elements

Author: manhunto

readme.md

@@ -94,7 +94,7 @@
 | [Day 5: Doesn't He Have Intern-Elves For This?](src/solutions/year2015/day05.rs) |   ⭐⭐   |            0.261 |            0.987 |
 | [Day 6: Probably a Fire Hazard](src/solutions/year2015/day06.rs)                 |   ⭐⭐   |          871.538 |          817.533 |
 | [Day 7: Some Assembly Required](src/solutions/year2015/day07.rs)                 |   ⭐⭐   |            0.308 |            0.293 |
-| [Day 8: Matchsticks](src/solutions/year2015/day08.rs)                            |   ⭐⭐   |            0.171 |            0.451 |
+| [Day 8: Matchsticks](src/solutions/year2015/day08.rs)                            |   ⭐⭐   |            0.052 |            0.129 |
 
 # TODO
 

src/solutions/year2015/day08.rs

@@ -42,8 +42,9 @@ impl Day08 {
                 break;
             }
 
-            if word.chars().nth(i).unwrap() == '\\' {
-                if word.chars().nth(i + 1).unwrap() == 'x' {
+            let slice = &word[i..=(i + 1)];
+            if slice.starts_with('\\') {
+                if slice == "\\x" {
                     i += 3;
                 } else {
                     i += 1;