From bc8de05d6951ffbdf22b4e050b51daf461a4d489 Mon Sep 17 00:00:00 2001
From: Bill Thiede <git@xinu.tv>
Date: Wed, 2 Dec 2020 19:57:26 -0800
Subject: [PATCH] Add alternate implementations for day 1, and create README of
 results.

---
 2020/README.md   | 33 +++++++++++++++++++++++++++++++++
 2020/src/day1.rs | 48 ++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 77 insertions(+), 4 deletions(-)
 create mode 100644 2020/README.md

diff --git a/2020/README.md b/2020/README.md
new file mode 100644
index 0000000..8c233ed
--- /dev/null
+++ b/2020/README.md
@@ -0,0 +1,33 @@
+# Results
+
+## Day 1
+```
+AOC 2020
+Day 1 - Part 1 - binary : 1006875
+        generator: 12.539µs,
+        runner: 373ns
+
+Day 1 - Part 1 - linear : 1006875
+        generator: 4.945µs,
+        runner: 7.727µs
+
+Day 1 - Part 1 - set : 1006875
+        generator: 16.721µs,
+        runner: 1.288µs
+
+Day 1 - Part 2 : 165026160
+        generator: 4.272µs,
+        runner: 1.225545ms
+```
+
+## Day 2
+```
+AOC 2020
+Day 2 - Part 1 : 640
+        generator: 1.821498ms,
+        runner: 115.525µs
+
+Day 2 - Part 2 : 472
+        generator: 1.52241ms,
+        runner: 10.459µs
+```
diff --git a/2020/src/day1.rs b/2020/src/day1.rs
index 78b1f57..59874ec 100644
--- a/2020/src/day1.rs
+++ b/2020/src/day1.rs
@@ -30,6 +30,8 @@
 //!
 //! In your expense report, what is the product of the three entries that sum to 2020?
 
+use std::collections::HashSet;
+
 use aoc_runner_derive::{aoc, aoc_generator};
 
 /// Reads text file containing one integer per line, and parses them into `Vec<u32>`.  Any
@@ -43,10 +45,8 @@ fn parse(input: &str) -> Vec<u32> {
 }
 
 /// Finds pairs of numbers in `nums` that sum to 2020.  If no pairs are found, the function panics.
-/// TODO(wathiede): make a version that sorts or uses a hash for finding the match to compare
-/// benchmarks.
-#[aoc(day1, part1)]
-fn find_pair_2020(nums: &[u32]) -> u32 {
+#[aoc(day1, part1, linear)]
+fn find_pair_2020_linear(nums: &[u32]) -> u32 {
     for (idx, first) in nums.iter().enumerate() {
         for second in nums.iter().skip(idx + 1) {
             if first + second == 2020 {
@@ -57,6 +57,46 @@ fn find_pair_2020(nums: &[u32]) -> u32 {
     panic!("Couldn't find pair");
 }
 
+#[aoc_generator(day1, part1, binary)]
+fn parse_sorted(input: &str) -> Vec<u32> {
+    let mut nums: Vec<u32> = input
+        .split('\n')
+        .map(|line| line.parse().unwrap())
+        .collect();
+    nums.sort();
+    nums
+}
+
+#[aoc(day1, part1, binary)]
+fn find_pair_2020_binary(nums: &[u32]) -> u32 {
+    for first in nums.iter() {
+        let diff = 2020 - first;
+        if nums.binary_search(&diff).is_ok() {
+            return first * diff;
+        }
+    }
+    panic!("Couldn't find pair");
+}
+
+#[aoc_generator(day1, part1, set)]
+fn parse_set(input: &str) -> HashSet<u32> {
+    input
+        .split('\n')
+        .map(|line| line.parse().unwrap())
+        .collect()
+}
+
+#[aoc(day1, part1, set)]
+fn find_pair_2020_set(nums: &HashSet<u32>) -> u32 {
+    for first in nums.iter() {
+        let diff = 2020 - first;
+        if nums.contains(&diff) {
+            return first * diff;
+        }
+    }
+    panic!("Couldn't find pair");
+}
+
 /// Finds triple of numbers in `nums` that sum to 2020.  If no triple is found, the function
 /// panics.
 #[aoc(day1, part2)]