{"header":{"message":"2021: day 4 solution","description":null,"timestamp":"2021-12-07T20:55:07.397123Z","authors":[{"email":"quick.dudley@gmail.com","full_name":"Jeremy List","name":"quickdudley"}]},"hash":"ZW7LNZTW4AZWJBHXZ5IU25PXTVFBAE5NPP7OD3JJNS54WCWYQ34QC","authors":[],"deps":{"hashes":[["ZW7LNZTW4AZWJBHXZ5IU25PXTVFBAE5NPP7OD3JJNS54WCWYQ34QC","2021: day 4 solution"],["AA",null],["HUHAFQLN6Q6U7CPR2SPPEPLE5LMCR53UA2GJ7LUVSHFXQPCGIYAQC","2021 day 1"]],"deps":["HUHAFQLN6Q6U7CPR2SPPEPLE5LMCR53UA2GJ7LUVSHFXQPCGIYAQC"],"known":[]},"hunks":[{"FileAdd":{"meta":{"basename":"day3.rs","metadata":0},"context":[{"change":2,"pos":16}],"contents":[{"Add":"#[derive(Clone, Copy, Debug)]"},{"Add":"struct BitCount {"},{"Add":" ones: u64,"},{"Add":" zeros: u64,"},{"Add":"}"},{"Add":""},{"Add":"impl BitCount {"},{"Add":" fn new() -> Self {"},{"Add":" Self { ones: 0, zeros: 0 }"},{"Add":" }"},{"Add":""},{"Add":" fn count_char(&mut self, c: char) {"},{"Add":" match c {"},{"Add":" '1' => self.count_one(),"},{"Add":" '0' => self.count_zero(),"},{"Add":" _ => (),"},{"Add":" }"},{"Add":" }"},{"Add":""},{"Add":" fn count_bit(&mut self, b: bool) {"},{"Add":" if b {"},{"Add":" self.count_one()"},{"Add":" } else {"},{"Add":" self.count_zero()"},{"Add":" }"},{"Add":" }"},{"Add":""},{"Add":" fn count_one(&mut self) {"},{"Add":" self.ones += 1;"},{"Add":" }"},{"Add":""},{"Add":" fn count_zero(&mut self) {"},{"Add":" self.zeros += 1;"},{"Add":" }"},{"Add":""},{"Add":" fn gamma(&self) -> bool {"},{"Add":" self.ones >= self.zeros"},{"Add":" }"},{"Add":""},{"Add":" fn epsilon(&self) -> bool {"},{"Add":" self.zeros > self.ones"},{"Add":" }"},{"Add":"}"},{"Add":""},{"Add":"impl Default for BitCount {"},{"Add":" fn default() -> Self {"},{"Add":" Self::new()"},{"Add":" }"},{"Add":"}"},{"Add":""},{"Add":"struct StretchZip<'a, Item, Rhs> {"},{"Add":" lhs: &'a mut Vec,"},{"Add":" ix: usize,"},{"Add":" rhs: Rhs,"},{"Add":"}"},{"Add":""},{"Add":"impl<'a, Item: Default, Rhs: Iterator> StretchZip<'a,Item,Rhs> {"},{"Add":" fn new(lhs: &'a mut Vec, rhs: Rhs) -> Self {"},{"Add":" Self { lhs, ix: 0, rhs }"},{"Add":" }"},{"Add":"}"},{"Add":""},{"Add":"impl<'a, Item: Default, Rhs: Iterator> Iterator for StretchZip<'a,Item,Rhs> {"},{"Add":" type Item = (&'a mut Item, ::Item);"},{"Add":""},{"Add":" fn next(&mut self) -> Option<(&'a mut Item, ::Item)> {"},{"Add":" let r = self.rhs.next()?;"},{"Add":" if self.ix >= self.lhs.len() {"},{"Add":" self.lhs.push(::default());"},{"Add":" }"},{"Add":" let l = unsafe {"},{"Add":" std::mem::transmute::<&mut Item, &'a mut Item>(self.lhs.get_mut(self.ix)?)"},{"Add":" };"},{"Add":" self.ix += 1;"},{"Add":" Some((l,r))"},{"Add":" }"},{"Add":"}"},{"Add":""},{"Add":"trait CounterList {"},{"Add":" fn count>(&mut self, item: I);"},{"Add":"}"},{"Add":""},{"Add":"impl CounterList for Vec {"},{"Add":" fn count>(&mut self, item: I) {"},{"Add":" for (counter, bit) in StretchZip::new(self, item) {"},{"Add":" counter.count_char(bit);"},{"Add":" }"},{"Add":" }"},{"Add":"}"},{"Add":""},{"Add":"fn life_support(field: bool, readings: &Vec>) -> u64 {"},{"Add":" let mut remaining_1 = Vec::new();"},{"Add":" let mut remaining_2 = Vec::new();"},{"Add":" for ix in 0 .. readings[0].len() {"},{"Add":" let (source, sink) = if ix == 0 {"},{"Add":" (readings, &mut remaining_1)"},{"Add":" } else if ix % 2 == 0 {"},{"Add":" (&remaining_2, &mut remaining_1)"},{"Add":" } else {"},{"Add":" (&remaining_1, &mut remaining_2)"},{"Add":" };"},{"Add":" let mut counter = BitCount::new();"},{"Add":" for reading in source.iter() {"},{"Add":" counter.count_bit(reading[ix]);"},{"Add":" }"},{"Add":" let target = if field {"},{"Add":" counter.gamma()"},{"Add":" } else {"},{"Add":" counter.epsilon()"},{"Add":" };"},{"Add":" sink.clear();"},{"Add":" sink.extend(source.iter().filter(|reading| reading[ix] == target).cloned());"},{"Add":" match sink.len() {"},{"Add":" 0 => { sink.extend(source.iter().cloned()); }"},{"Add":" 1 => { return from_bits(sink[0].iter().copied()); }"},{"Add":" _ => {}"},{"Add":" }"},{"Add":" }"},{"Add":" from_bits(if remaining_1.len() <= remaining_2.len() {"},{"Add":" &remaining_1[0]"},{"Add":" } else {"},{"Add":" &remaining_2[0]"},{"Add":" }.iter().copied())"},{"Add":"}"},{"Add":""},{"Add":"fn from_bits>(source: I) -> u64 {"},{"Add":" let mut result = 0;"},{"Add":" for b in source {"},{"Add":" result = result * 2 + (if b { 1 } else { 0 });"},{"Add":" }"},{"Add":" result"},{"Add":"}"},{"Add":""},{"Add":"fn main() {"},{"Add":" use std::io::BufRead;"},{"Add":" let filename = std::env::args().nth(1).expect(\"Expected filename\");"},{"Add":" let file = std::io::BufReader::new("},{"Add":" std::fs::File::open(>::as_ref(&filename)).unwrap()"},{"Add":" );"},{"Add":" let mut counters = Vec::new();"},{"Add":" let mut record = Vec::new();"},{"Add":" for line in file.lines().filter_map(Result::ok) {"},{"Add":" counters.count(line.chars());"},{"Add":" record.push(line.chars().filter_map(|c| match c {"},{"Add":" '0' => Some(false),"},{"Add":" '1' => Some(true),"},{"Add":" _ => None"},{"Add":" }).collect::>())"},{"Add":" };"},{"Add":" let gamma = from_bits(counters.iter().map(BitCount::gamma));"},{"Add":" println!(\"Gamma: {}\", gamma);"},{"Add":" let epsilon = from_bits(counters.iter().map(BitCount::epsilon));"},{"Add":" println!(\"Epsilon: {}\", epsilon);"},{"Add":" println!(\"Product: {}\", gamma * epsilon);"},{"Add":" let oxygen = life_support(true, &record);"},{"Add":" println!(\"Oxygen: {}\", oxygen);"},{"Add":" let scrubber = life_support(false, &record);"},{"Add":" println!(\"CO2 Scrubber: {}\", scrubber);"},{"Add":" println!(\"Product: {}\", oxygen * scrubber);"},{"Add":"}"}]}}],"owner":"quickdudley","repo":"adventofcode","token":"AG5CJDeEnErg0Oe8MYNiOguHVFoLHGSyher2uabRyZo=","login":null}

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