day 5

day-05/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "day-05"
+version = "0.1.0"

day-05/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "day-05"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

day-05/src/main.rs

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+const INPUT: &str = include_str!(concat!(env!("CARGO_MANIFEST_DIR"), "/input.txt"));
+
+fn main() {
+    let mut deps = [[false; 100]; 100];
+
+    let mut lines = INPUT.lines();
+    while let Some(line) = lines.next() {
+        if line.is_empty() { break }
+        let (first, second) = line.split_at(line.find("|").unwrap());
+        let first = str::parse::<u8>(first).unwrap();
+        let second = str::parse::<u8>(second.trim().trim_start_matches('|')).unwrap();
+
+        deps[first as usize][second as usize] = true;
+    }
+
+
+    let sequences = lines.map(|line| {
+        line.split_terminator(",")
+            .map(|num| {
+                str::parse::<u8>(num).unwrap()
+            })
+    });
+
+    {
+        let mut sequences = sequences.clone();
+
+        let mut total = 0;
+        while let Some(line) = sequences.next() {
+            let numbers: Vec<_> = line.collect();
+
+            if ordered(deps, &numbers[..]) {
+                total += u32::from(numbers[numbers.len() / 2]);
+            }
+        }
+
+        println!("Part 1: {}", total);
+    }
+
+    {
+        let mut sequences = sequences.clone();
+
+        let mut total = 0;
+        while let Some(line) = sequences.next() {
+            let mut numbers: Vec<_> = line.collect();
+
+            if !ordered(deps, &numbers[..]) {
+                order(deps, &mut numbers);
+                total += u32::from(numbers[numbers.len() / 2]);
+            }
+        }
+
+        println!("Part 2: {}", total);
+    }
+}
+
+fn ordered(graph: [[bool; 100]; 100], list: &[u8]) -> bool {
+    for i in 0..list.len() {
+        for j in (i + 1)..list.len() {
+            if graph[list[j] as usize][list[i] as usize] {
+                return false
+            }
+        }
+    }
+    true
+}
+
+fn order(graph: [[bool; 100]; 100], list: &mut Vec<u8>) {
+    use std::cmp::Ordering;
+    list.sort_by(|&first, &second| {
+        if graph[first as usize][second as usize] {
+            Ordering::Less
+        } else if graph[second as usize][first as usize] {
+            Ordering::Greater
+        } else {
+            Ordering::Equal
+        }
+    })
+}
+