42 lines
1.6 KiB
Rust
42 lines
1.6 KiB
Rust
use std::fs;
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fn first_puzzle(input: &String) {
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// Go through each line and subtract it to the previous one, keeping only the positive results
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// and counting them, knowing that the first diff is invalid.
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let count = input.lines().scan(0, |current, line| {
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let previous = *current;
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*current = line.parse::<i32>().unwrap();
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Some(*current - previous)}).filter(|diff| diff.is_positive()).count() - 1;
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println!("Count of single increases : {}", count);
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}
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fn second_puzzle(input: &String) {
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// For each input, add it to a circular buffer whose write position is stored at the end.
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// For all but the first two elements, output the sum of the circular buffer.
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let count = input.lines().scan([0; 4], |sliding_window: &mut [i32; 4], line|{
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let place = sliding_window[3];
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sliding_window[(place % 3) as usize] = line.parse::<i32>().unwrap();
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sliding_window[3] = place + 1;
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if sliding_window[3] < 3 {
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Some(-1)
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} else {
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Some(sliding_window[0..3].iter().sum::<i32>())
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}
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// Filter out the first two elements, can't generate a three-element sum.
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}).filter(|sum| !sum.is_negative()).scan(0, |current, sum| {
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// Subtract each successive elements, similarly to the first solution.
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let previous = *current;
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*current = sum;
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Some(*current - previous)}).filter(|diff| diff.is_positive()).count() - 1;
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println!("Count of triple sums increasing : {}", count);
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}
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fn main() {
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let contents = fs::read_to_string("../input.txt").expect("Could not open file.");
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first_puzzle(&contents);
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second_puzzle(&contents);
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0;
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}
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