81 lines
3.0 KiB
Rust
81 lines
3.0 KiB
Rust
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use std::cmp;
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use std::collections::HashMap;
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use std::fs;
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// Extract all numbers, digits and letter written digits
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fn extract_numbers(line: &str) -> Vec<u32> {
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let written_digits: Vec<&str> = vec![
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"one", "two", "three", "four", "five", "six", "seven", "eight", "nine",
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];
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let mut max_tail_overlaps: HashMap<&str, u32> = HashMap::new();
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// Compute the size of the suffix of number i overlaping with prefix of number j:
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for suffix_number in &written_digits {
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max_tail_overlaps.insert(suffix_number.clone(), 0);
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for prefix_number in &written_digits {
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if suffix_number != prefix_number {
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let mut overlap: u32 = 0;
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for i in 0..(cmp::min(prefix_number.len(), suffix_number.len())) {
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if suffix_number.chars().nth_back(i) == prefix_number.chars().nth(i) {
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overlap += 1;
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} else {
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break;
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}
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}
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if overlap > max_tail_overlaps[suffix_number] {
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max_tail_overlaps.insert(suffix_number, overlap);
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}
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}
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}
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}
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let mut numbers: Vec<u32> = Vec::new();
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let mut current_digit_word: String = "".to_owned();
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for character in line.chars() {
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if character.is_digit(10) {
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numbers.push(character.to_digit(10).unwrap());
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current_digit_word = "".to_owned(); // Reset writing word
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} else {
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current_digit_word.push(character);
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// Check for the presence of any of the digit words
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for (index, digit_writing) in written_digits.iter().enumerate() {
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let word_length = digit_writing.len();
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let positions: Vec<(usize, &str)> =
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current_digit_word.match_indices(digit_writing).collect();
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if positions.len() > 0 {
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let digit = index as u32 + 1;
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numbers.push(digit);
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let start_position = positions[0].0;
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let end_position =
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start_position + word_length - max_tail_overlaps[digit_writing] as usize;
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let current_digit_word_slice = ¤t_digit_word[end_position..];
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current_digit_word = current_digit_word_slice.to_owned();
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}
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}
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}
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}
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numbers
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}
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// Extract number including letters
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fn extract_number(line: &str) -> u32 {
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let numbers: Vec<u32> = extract_numbers(line);
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let first: u32 = numbers[0];
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let last: u32 = numbers[numbers.len() - 1];
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let number: u32 = first * 10 + last;
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number
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}
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fn main() {
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let input_filename: &str = "../data/input.txt";
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let contents =
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fs::read_to_string(input_filename).expect("Should have been able to read the file");
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let mut sum: u32 = 0;
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for line in contents.lines() {
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let number = extract_number(line);
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println!("{}\t{:?}", line, number);
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sum += number;
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}
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println!("{:?}", sum);
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}
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