From 11b2fd042a72eb93fb0741e2dec7d0ec035178f8 Mon Sep 17 00:00:00 2001
From: Arne Dußin
Date: Wed, 8 Dec 2021 10:05:20 +0100
Subject: Yes, I totally didn't forget to commit

---
 src/day_7.rs | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 src/day_7.rs

(limited to 'src/day_7.rs')

diff --git a/src/day_7.rs b/src/day_7.rs
new file mode 100644
index 0000000..e14512a
--- /dev/null
+++ b/src/day_7.rs
@@ -0,0 +1,58 @@
+use std::cmp;
+
+fn abs_diff(a: u32, b: u32) -> u32 { cmp::max(a, b) - cmp::min(a, b) }
+
+fn fuel_required_constant(positions: &[u32], destination: u32) -> u32
+{
+    positions.iter().fold(0, |fuel_total, pos| {
+        fuel_total + abs_diff(*pos, destination)
+    })
+}
+
+fn fuel_required_linear(positions: &[u32], destination: u32) -> u32
+{
+    let fuel_required = |pos, dest| {
+        let distance = abs_diff(pos, dest);
+        // Get total fuel cost by adding all integers until distance on top of each
+        // other
+        (distance * (distance + 1)) / 2
+    };
+
+    positions.iter().fold(0, |fuel_total, pos| {
+        fuel_total + fuel_required(*pos, destination)
+    })
+}
+
+fn part1(positions: &[u32])
+{
+    // Stupid approach: Try all positions out
+    let mut min_required = fuel_required_constant(positions, 0);
+    for pos in 1..positions.len() {
+        min_required = cmp::min(fuel_required_constant(positions, pos as u32), min_required);
+    }
+
+    println!("Solution to part 1: {}", min_required);
+}
+
+fn part2(positions: &[u32])
+{
+    // Stupid approach: Try all positions out
+    let mut min_required = fuel_required_linear(positions, 0);
+    for pos in 1..positions.len() {
+        min_required = cmp::min(fuel_required_linear(positions, pos as u32), min_required);
+    }
+
+    println!("Solution to part 2: {}", min_required);
+}
+
+pub fn run(input: Vec<String>)
+{
+    let positions: Vec<u32> = input
+        .iter()
+        .map(|s| s.split(',').map(|s| s.parse().unwrap()))
+        .flatten()
+        .collect();
+
+    part1(&positions);
+    part2(&positions);
+}
-- 
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