Day 3 Part 2

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"

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);
+    }
 }