From df80545a60b409350ea18e97cb6a1e35801f893f Mon Sep 17 00:00:00 2001
From: Anthony Cicchetti <anthony@anthonycicchetti.com>
Date: Fri, 3 Dec 2021 17:03:22 -0500
Subject: [PATCH] Day 3 Part 2

---
 day_03/Cargo.toml |  1 -
 day_03/src/lib.rs | 84 +++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 81 insertions(+), 4 deletions(-)

diff --git a/day_03/Cargo.toml b/day_03/Cargo.toml
index 3981393..1f992a4 100644
--- a/day_03/Cargo.toml
+++ b/day_03/Cargo.toml
@@ -6,4 +6,3 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-bitvec = "1.0.0-rc1"
diff --git a/day_03/src/lib.rs b/day_03/src/lib.rs
index 893b49a..55430be 100644
--- a/day_03/src/lib.rs
+++ b/day_03/src/lib.rs
@@ -1,4 +1,5 @@
-use std::ops::BitXor;
+use std::ops::{BitXor, Deref};
+use std::rc::Rc;
 
 fn parse_input(input: &str) -> Vec<Vec<bool>> {
     input
@@ -19,6 +20,7 @@ fn make_bit_field(inp_str: &str) -> Vec<bool> {
     out
 }
 
+#[derive(Debug)]
 struct BoolVec(Vec<bool>);
 
 impl From<BoolVec> for usize {
@@ -128,6 +130,82 @@ pub fn part1(input: &str) -> usize {
 ///
 /// Use the binary numbers in your diagnostic report to calculate the oxygen generator rating and CO2 scrubber rating, then multiply them together. What is the life support rating of the submarine? (Be sure to represent your answer in decimal, not binary.)
 pub fn part2(input: &str) -> usize {
-    let a = parse_input(input);
-    0
+    let input = Rc::new(parse_input(input));
+    let ogr = get_oxygen_generator_rating(input.clone());
+    let csr = get_co2_scrubber_rating(input.clone());
+
+    ogr * csr
+}
+
+fn get_oxygen_generator_rating(input: Rc<Vec<Vec<bool>>>) -> usize {
+    let mut input = input.deref().clone();
+    let mut index_to_compare = 0;
+    while input.len() > 1 {
+        let mut most_common_indices = vec![];
+        for idx in 0..input[0].len() {
+            match most_common_in_index(&input, idx) {
+                true => most_common_indices.push(true),
+                false => most_common_indices.push(false),
+            }
+        }
+        let (trues, falses): (Vec<Vec<bool>>, Vec<Vec<bool>>) = input
+            .clone()
+            .into_iter()
+            .partition(|item| item[index_to_compare]);
+        if trues.len() >= falses.len() {
+            input = trues;
+        } else {
+            input = falses;
+        }
+        index_to_compare += 1;
+    }
+
+    usize::from(BoolVec(input[0].clone()))
+}
+
+fn get_co2_scrubber_rating(input: Rc<Vec<Vec<bool>>>) -> usize {
+    let mut input = input.deref().clone();
+    let mut index_to_compare = 0;
+    while input.len() > 1 {
+        let mut most_common_indices = vec![];
+        for idx in 0..input[0].len() {
+            match most_common_in_index(&input, idx) {
+                true => most_common_indices.push(true),
+                false => most_common_indices.push(false),
+            }
+        }
+        let (trues, falses): (Vec<Vec<bool>>, Vec<Vec<bool>>) = input
+            .clone()
+            .into_iter()
+            .partition(|item| item[index_to_compare]);
+        if trues.len() >= falses.len() {
+            input = falses;
+        } else {
+            input = trues;
+        }
+        index_to_compare += 1;
+    }
+
+    usize::from(BoolVec(input[0].clone()))
+}
+
+#[cfg(test)]
+mod test {
+    use crate::{get_co2_scrubber_rating, get_oxygen_generator_rating, parse_input};
+
+    #[test]
+    fn oxygen_generator_rating_works() {
+        let input = std::rc::Rc::new(parse_input(
+            "00100 11110 10110 10111 10101 01111 00111 11100 10000 11001 00010 01010",
+        ));
+        assert_eq!(get_oxygen_generator_rating(input), 23);
+    }
+
+    #[test]
+    fn co2_scrubber_generator_rating_works() {
+        let input = std::rc::Rc::new(parse_input(
+            "00100 11110 10110 10111 10101 01111 00111 11100 10000 11001 00010 01010",
+        ));
+        assert_eq!(get_co2_scrubber_rating(input), 10);
+    }
 }