Day 4

day4/Cargo.lock

@@ -0,0 +1,77 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "aho-corasick"
+version = "1.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b2969dcb958b36655471fc61f7e416fa76033bdd4bfed0678d8fee1e2d07a1f0"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
+name = "anyhow"
+version = "1.0.75"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a4668cab20f66d8d020e1fbc0ebe47217433c1b6c8f2040faf858554e394ace6"
+
+[[package]]
+name = "day4"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "itertools",
+ "regex",
+]
+
+[[package]]
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+
+[[package]]
+name = "itertools"
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+dependencies = [
+ "either",
+]
+
+[[package]]
+name = "memchr"
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+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-automata",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-automata"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5f804c7828047e88b2d32e2d7fe5a105da8ee3264f01902f796c8e067dc2483f"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-syntax"
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day4/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "day4"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+anyhow = "1.0.75"
+itertools = "0.12.0"
+regex = "1.10.2"

day4/src/main.rs

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+use std::{io::stdin, str::FromStr};
+use anyhow::{anyhow, Result, Error};
+use itertools::Itertools;
+
+struct Card {
+    id: u8,
+    drawn: [bool; 100],
+    chosen:[bool; 100],
+    wins: u8,
+}
+
+impl Card {
+    fn value(&self) -> usize {
+        self.wins
+            .checked_sub(1)
+            .map(|e| 2_usize.pow(e as u32))
+            .unwrap_or(0)
+    }
+}
+
+impl FromStr for Card {
+    type Err = Error;
+    fn from_str(s: &str) -> Result<Self> {
+        let (id_s, drawn_s, chosen_s) = s.split(&[':','|'])
+            .collect_tuple()
+            .ok_or_else(||anyhow!("Bad line format {s}"))?;
+        let id = id_s.strip_prefix("Card ")
+                .ok_or_else(|| anyhow!("Bad header {id_s}"))?
+                .trim()
+                .parse()?;
+
+        let mut drawn = [false; 100];
+        let mut chosen = [false; 100];
+        let mut wins = 0;
+
+        for d in drawn_s.trim().split_whitespace() {
+            drawn[d.parse::<usize>()?] = true;
+        }
+        for c in chosen_s.trim().split_whitespace() {
+            let c: usize = c.parse()?;
+            chosen[c] = true;
+            if drawn[c] { wins += 1 }
+        }
+
+        Ok(Card { id, drawn, chosen, wins })
+    }
+}
+
+fn read() -> Result<Vec<Card>> {
+    stdin()
+        .lines()
+        .map(|s| s?.parse())
+        .collect()
+}
+
+fn main() -> Result<()> {
+    let cards = read()?;
+    let score1: usize = cards.iter().map(Card::value).sum();
+    println!("score is {score1}");
+
+    let mut counts: Vec<usize> = cards.iter().map(|_| 1).collect();
+    for i in 0..counts.len() {
+        let amount = counts[i];
+        let wins = cards[i].wins as usize;
+        for other in &mut counts[i+1..][..wins] {
+            *other += amount;
+        }
+    }
+    let total: usize = counts.iter().sum();
+    println!("Total cards {total}");
+    Ok(())
+}