1 files changed, 71 insertions(+), 4 deletions(-)

M day3/src/main.rs

@@ 1,5 1,6 @@
-use anyhow::{anyhow, Result};
+use anyhow::Result;
 use std::io::{stdin, BufRead, BufReader};
+use std::time::Instant;
 
 fn main() -> Result<()> {
     let data: Vec<String> = {


@@ 33,6 34,8 @@ fn counts(data: &Vec<String>) -> Vec<usize> {
 }
 
 fn part1(data: &Vec<String>) {
+    let now = Instant::now();
+
     let n = data.len();
     let cs = counts(data);
     let mut epsilon: u64 = 0;


@@ 48,10 51,74 @@ fn part1(data: &Vec<String>) {
         }
     }
     let mul = epsilon * gamma;
+
+    let elapsed = now.elapsed();
     println!(
-        "Part 1 => {} {:b} * {} {:b} = {}",
-        epsilon, epsilon, gamma, gamma, mul
+        "Part 1 [{}s {}us {}ns] => {} {:b} * {} {:b} = {}",
+        elapsed.as_secs_f64(),
+        elapsed.as_micros(),
+        elapsed.as_nanos(),
+        epsilon,
+        epsilon,
+        gamma,
+        gamma,
+        mul
     );
 }
 
-fn part2(data: &Vec<String>) {}
+fn count_col(data: &Vec<String>, col: usize) -> usize {
+    let mut n: usize = 0;
+    for row in data.iter() {
+        if row.as_bytes()[col] == b'1' {
+            n += 1;
+        }
+    }
+    n
+}
+
+fn part2(data: &Vec<String>) {
+    let now = Instant::now();
+
+    let columns = data[0].len();
+
+    let mut oxygen = data.to_vec();
+    let mut scrubber = data.to_vec();
+
+    let keep = |i: usize, row: &String, c: u8| row.as_bytes()[i] == c;
+
+    for col in 0..columns {
+        let ones = count_col(&oxygen, col);
+        let zeroes = oxygen.len() - ones;
+        let find = if ones >= zeroes { b'1' } else { b'0' };
+        oxygen.retain(|row| keep(col, row, find));
+        if oxygen.len() == 1 {
+            break;
+        }
+    }
+
+    for col in 0..columns {
+        let ones = count_col(&scrubber, col);
+        let zeroes = scrubber.len() - ones;
+        let find = if zeroes <= ones { b'0' } else { b'1' };
+        scrubber.retain(|row| keep(col, row, find));
+        if scrubber.len() == 1 {
+            break;
+        }
+    }
+
+    let oxygen_dec = u64::from_str_radix(oxygen[0].as_str(), 2).unwrap();
+    let scrubber_dec = u64::from_str_radix(scrubber[0].as_str(), 2).unwrap();
+
+    let elapsed = now.elapsed();
+    println!(
+        "Part 2 [{}s {}us {}ns] => {} {:?} * {} {:?} = {}",
+        elapsed.as_secs_f64(),
+        elapsed.as_micros(),
+        elapsed.as_nanos(),
+        oxygen_dec,
+        oxygen[0],
+        scrubber_dec,
+        scrubber[0],
+        oxygen_dec * scrubber_dec,
+    );
+}