From 55272aea40213dcfc61c7b1b20a10ad644c6851c Mon Sep 17 00:00:00 2001
From: Greg Burri <greg.burri@gmail.com>
Date: Sat, 3 Dec 2022 19:15:15 +0100
Subject: [PATCH] Add a parsing function to simplify the process

---
 src/day03.rs | 79 ++++++++++++++++++++++++++--------------------------
 src/main.rs  |  7 ++---
 2 files changed, 42 insertions(+), 44 deletions(-)

diff --git a/src/day03.rs b/src/day03.rs
index 5deba68..b38bc82 100644
--- a/src/day03.rs
+++ b/src/day03.rs
@@ -2,24 +2,34 @@ use std::io::BufRead;
 
 use itertools::Itertools;
 
-pub fn priority_sum<R>(reader: R) -> i32
-where
-    R: BufRead
-{
+pub fn parse(s: &str) -> Vec<Vec<u8>> {
+    s.lines()
+        .map(|l| {
+            l.as_bytes().into_iter().map(letter_to_priority).collect_vec()
+        }).collect()
+}
+
+fn letter_to_priority(v: &u8) -> u8 {
+    if *v >= 97 { // >= 'a'
+        v - 96
+    } else { // < 'a'
+        v - 38
+    }
+}
+
+pub fn priority_sum(rucksacks: &[Vec<u8>]) -> i32 {
     let mut sum = 0;
-    let mut item_count = [0i32; 52];
-    for l in reader.lines() {
+    let mut item_count = [0u8; 52];
+    for r in rucksacks {
         item_count.fill(0);
-        let l = l.unwrap();
-        let items = l.as_bytes();
-        for i in 0..items.len() / 2 {
-            let v = letter_to_priority(items[i]);
-            item_count[v as usize - 1] += 1;
+
+        for i in 0..r.len() / 2 {
+            item_count[r[i] as usize - 1] += 1;
         }
-        for i in items.len() / 2..items.len() {
-            let v = letter_to_priority(items[i]);
-            if item_count[v as usize - 1] > 0 {
-                sum += v as i32;
+
+        for i in r.len() / 2..r.len() {
+            if item_count[r[i] as usize - 1] > 0 {
+                sum += r[i] as i32;
                 break;
             }
         }
@@ -27,35 +37,26 @@ where
     sum
 }
 
-pub fn badge_sum<R>(reader: R) -> i32
-where
-    R: BufRead
-{
+pub fn badge_sum(rucksacks: &[Vec<u8>]) -> i32 {
     let mut sum = 0;
     let mut item_set = [0u8; 52];
-    for group in reader.lines().chunks(3).into_iter() {
+    for group in rucksacks.chunks(3).into_iter() {
         item_set.fill(0);
-        for (i, rucksack) in group.enumerate() {
-            let items = rucksack.unwrap();
-            for b in items.as_bytes().into_iter() {
-                let v = letter_to_priority(*b);
-                if i == 2 && item_set[v as usize - 1] == 3 {
-                    sum += v as i32;
-                    break;
-                }
-                item_set[v as usize - 1] |= 1 << i;
+
+        for i in 0..2 {
+            for b in group[i].iter() {
+                item_set[*b as usize - 1] |= 1 << i;
             }
         }
-    }
-    sum
-}
 
-fn letter_to_priority(v: u8) -> u8 {
-    if v >= 97 { // >= 'a'
-        v - 96
-    } else { // < 'a'
-        v - 38
+        for b in group[2].iter() {
+            if item_set[*b as usize - 1] == 3 {
+                sum += *b as i32;
+                break;
+            }
+        }
     }
+    sum
 }
 
 #[cfg(test)]
@@ -72,7 +73,7 @@ wMqvLMZHhHMvwLHjbvcjnnSBnvTQFn
 ttgJtRGJQctTZtZT
 CrZsJsPPZsGzwwsLwLmpwMDw";
 
-        assert_eq!(priority_sum(rucksacks.as_bytes()), 157);
+        assert_eq!(priority_sum(&parse(rucksacks)), 157);
     }
 
     #[test]
@@ -85,6 +86,6 @@ wMqvLMZHhHMvwLHjbvcjnnSBnvTQFn
 ttgJtRGJQctTZtZT
 CrZsJsPPZsGzwwsLwLmpwMDw";
 
-        assert_eq!(badge_sum(rucksacks.as_bytes()), 70);
+        assert_eq!(badge_sum(&parse(rucksacks)), 70);
     }
 }
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index 66d8ef0..e7b4bed 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -20,11 +20,8 @@ fn day02() -> String {
 }
 
 fn day03() -> String {
-    let mut f = fs::File::open("data/day03.input").unwrap();
-    let part1 = day03::priority_sum(BufReader::new(f.try_clone().unwrap()));
-    let _ = f.seek(SeekFrom::Start(0));
-    let part2 = day03::badge_sum(BufReader::new(f));
-    format!("part1: {}, part2: {}", part1, part2)
+    let rucksacks = day03::parse(&fs::read_to_string("data/day03.input").unwrap());
+    format!("part1: {}, part2: {}", day03::priority_sum(&rucksacks), day03::badge_sum(&rucksacks))
 }
 
 fn format_micros(t: u128) -> String {
-- 
2.45.2