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+extern crate regex;
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+
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+use std::error::Error;
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+use std::fs::File;
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+use std::io::{BufRead, BufReader};
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+use std::fmt;
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+use std::collections::HashMap;
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+
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+use regex::{Regex, Captures};
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+
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+const INPUT: &str = "inputs/3.txt";
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+
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+#[derive(Debug, PartialEq)]
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+struct Claim {
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+ id: u32,
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+ left: u32,
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+ top: u32,
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+ width: u32,
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+ height: u32,
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+}
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+
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+#[derive(Debug, PartialEq, Eq, Hash)]
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+struct Point {
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+ x: u32,
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+ y: u32,
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+}
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+
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+#[derive(Debug, Clone, PartialEq)]
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+struct MalformedClaim {
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+ details: String
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+}
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+
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+impl MalformedClaim {
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+ fn new(msg: &str) -> MalformedClaim {
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+ MalformedClaim{ details: msg.to_string() }
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+ }
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+}
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+
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+impl fmt::Display for MalformedClaim {
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+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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+ write!(f, "{}", self.details)
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+ }
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+}
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+
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+impl Error for MalformedClaim {
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+ fn description(&self) -> &str {
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+ &self.details
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+ }
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+}
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+
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+pub fn solve_part1() -> Result<u32, Box<Error>> {
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+ Ok(count_overlapping_claimed_points(read_claims(INPUT)?))
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+}
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+
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+fn count_overlapping_claimed_points(claims: Vec<Claim>) -> u32 {
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+ let mut claimed_points: HashMap<Point, u32> = HashMap::new();
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+ for claim in claims {
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+ for point in list_points_in_claim(claim) {
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+ let current_point = claimed_points.get(&point).unwrap_or(&0);
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+ claimed_points.insert(point, current_point + 1);
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+ }
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+ }
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+ return claimed_points.values().fold(0, |acc, claims| {
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+ if claims > &1 {
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+ return acc + 1
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+ }
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+ acc
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+ })
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+}
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+
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+fn list_points_in_claim(claim: Claim) -> Vec<Point> {
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+ let mut points = Vec::new();
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+ for x in 0..claim.width {
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+ for y in 0..claim.height {
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+ points.push(Point { x: claim.left + x, y: claim.top + y });
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+ }
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+ }
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+ points
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+}
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+
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+fn read_claims(filename: &str) -> Result<Vec<Claim>, Box<Error>> {
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+ let mut claims: Vec<Claim> = Vec::new();
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+ let claim_regex =
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+ Regex::new(r"#(?P<id>\d+) @ (?P<left>\d+),(?P<top>\d+): (?P<width>\d+)x(?P<height>\d+)")?;
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+ let file = File::open(filename)?;
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+ for line in BufReader::new(file).lines() {
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+ match claim_regex.captures(&line?) {
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+ Some(captures) => {
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+ let claim = Claim {
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+ id: get_captured_field(&captures, "id")?,
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+ left: get_captured_field(&captures, "left")?,
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+ top: get_captured_field(&captures, "top")?,
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+ width: get_captured_field(&captures, "width")?,
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+ height: get_captured_field(&captures, "height")?,
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+ };
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+ claims.push(claim);
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+ },
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+ None => return Err(Box::new(MalformedClaim {
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+ details: "Malformed claim line, no fields could be found".to_string()
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+ })),
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+ };
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+ }
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+ Ok(claims)
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+}
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+
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+fn get_captured_field(captures: &Captures, field: &str) -> Result<u32, Box<Error>> {
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+ match captures.name(field) {
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+ Some(capture) => Ok(capture.as_str().parse()?),
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+ None => return Err(Box::new(MalformedClaim {
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+ details: format!("Malformed claim line, field {} could not be found", field)
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+ }))
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+ }
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+}
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+
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+
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+#[cfg(test)]
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+mod tests {
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+ use super::*;
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+
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+ const TEST_INPUT: &str = "inputs/3_test.txt";
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+ const TEST_INPUT_MALFORMED: &str = "inputs/3_test_malformed.txt";
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+
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+ #[test]
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+ fn reads_claims_file() {
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+ assert_eq!(read_claims(TEST_INPUT).unwrap(), vec![
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+ Claim { id: 1, left: 1, top: 3, width: 4, height: 4 },
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+ Claim { id: 2, left: 3, top: 1, width: 4, height: 4 },
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+ Claim { id: 3, left: 5, top: 5, width: 2, height: 2 },
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+ ]);
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+ }
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+
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+ #[test]
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+ fn errors_on_malformed_claims_file() {
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+ match read_claims(TEST_INPUT_MALFORMED) {
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+ Ok(_) => assert!(false, "read_claims should have returned an error"),
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+ Err(err) => assert_eq!(
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+ (*err).description(),
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+ "Malformed claim line, no fields could be found".to_string(),
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+ ),
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+ }
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+ }
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+
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+ #[test]
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+ fn lists_points_in_claim() {
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+ assert_eq!(list_points_in_claim(Claim { id: 1, left: 0, top: 0, width: 2, height: 2 }),
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+ vec![
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+ Point { x: 0, y: 0 },
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+ Point { x: 0, y: 1 },
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+ Point { x: 1, y: 0 },
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+ Point { x: 1, y: 1 },
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+ ]
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+ )
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+ }
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+
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+ #[test]
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+ fn counts_overlapping_claimed_points() {
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+ let test_claims = vec![
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+ Claim { id: 1, left: 1, top: 3, width: 4, height: 4 },
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+ Claim { id: 2, left: 3, top: 1, width: 4, height: 4 },
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+ Claim { id: 3, left: 5, top: 5, width: 2, height: 2 },
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+ ];
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+ assert_eq!(count_overlapping_claimed_points(test_claims), 4);
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+ }
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+}
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