From a2aa8a353f614416249d37b2f78ce0fb401a26cb Mon Sep 17 00:00:00 2001
From: kageru <kageru@encode.moe>
Date: Wed, 16 Dec 2020 16:12:41 +0100
Subject: [PATCH] Add helper

---
 2020/src/bin/day15.rs |  4 +++-
 2020/src/bin/day16.rs | 18 ++++--------------
 2020/src/common.rs    |  5 +++++
 3 files changed, 12 insertions(+), 15 deletions(-)

diff --git a/2020/src/bin/day15.rs b/2020/src/bin/day15.rs
index 2a13c50..f1265c4 100644
--- a/2020/src/bin/day15.rs
+++ b/2020/src/bin/day15.rs
@@ -1,6 +1,7 @@
 #![feature(test)]
 extern crate test;
 use std::collections::HashMap;
+use aoc2020::common::*;
 
 type Parsed = Vec<usize>;
 
@@ -8,8 +9,9 @@ fn read_input() -> String {
     String::from("15,12,0,14,3,1")
 }
 
+#[inline]
 fn parse_input(raw: &str) -> Parsed {
-    raw.split(',').filter_map(|x| x.parse().ok()).collect()
+    parse_nums(raw)
 }
 
 #[rustfmt::skip]
diff --git a/2020/src/bin/day16.rs b/2020/src/bin/day16.rs
index f0135ba..d081609 100644
--- a/2020/src/bin/day16.rs
+++ b/2020/src/bin/day16.rs
@@ -45,23 +45,13 @@ fn parse_input(raw: &str) -> Parsed {
     let (rules, my_ticket, nearby) = raw.split("\n\n").next_tuple().unwrap();
     Parsed {
         rules:          rules.lines().map_into().collect(),
-        my_ticket:      my_ticket
-            .split_once('\n')
-            .unwrap()
-            .1
-            .split(',')
-            .map(|n| n.parse().unwrap())
-            .collect(),
-        nearby_tickets: nearby
-            .lines()
-            .skip(1)
-            .map(|l| l.split(',').map(|n| n.parse().unwrap()).collect())
-            .collect(),
+        my_ticket:      parse_nums(my_ticket.split_once('\n').unwrap().1),
+        nearby_tickets: nearby.lines().skip(1).map(parse_nums).collect(),
     }
 }
 
-// Could be optimized by folding the ranges first to only have one lower and one upper (or even
-// just a single one if they’re continuous), but meh.
+// Could be optimized by merging overlapping ranges into one before checking all the tickets.
+// … or so I thought until I tried, benchmarked, and saw that that takes twice as long.
 fn part1(parsed: &Parsed) -> usize {
     parsed
         .nearby_tickets
diff --git a/2020/src/common.rs b/2020/src/common.rs
index 9d64604..9f77058 100644
--- a/2020/src/common.rs
+++ b/2020/src/common.rs
@@ -9,3 +9,8 @@ pub fn read_file(day: usize) -> String {
     )
     .unwrap()
 }
+
+#[inline]
+pub fn parse_nums(l: &str) -> Vec<usize> {
+    l.split(',').filter_map(|n| n.parse().ok()).collect()
+}