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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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