Add day 3 part 1

3 years ago · 739ed58abf
3 changed files with 147 additions and 0 deletions
--- a/input/day3
+++ b/input/day3
@ -0,0 +1,2 @@
+R1000,D722,L887,D371,R430,D952,R168,D541,L972,D594,R377,U890,R544,U505,L629,U839,L680,D863,L315,D10,L482,U874,L291,U100,R770,D717,L749,U776,L869,D155,R250,U672,L195,D991,L556,D925,R358,U296,R647,D652,L790,D780,L865,U405,L400,D160,L460,U50,R515,D666,R306,U746,R754,U854,L332,U254,R673,U795,R560,U69,L507,U332,L328,U547,L717,U291,R626,U868,L583,D256,R371,U462,R793,U559,L571,U270,R738,U425,L231,U549,L465,U21,L647,U43,R847,U104,L699,U378,L549,D975,R13,D306,R532,D730,L566,U846,L903,D224,R448,D424,L727,D199,L626,D872,L541,D786,L304,U462,R347,U379,R29,D556,L775,D768,L284,D480,R654,D659,R818,D57,L77,U140,R619,D148,R686,D461,L910,U244,R115,D769,R968,U802,L737,U868,R399,D150,L791,U579,L856,D11,R115,U522,L443,D575,L133,U750,R437,U718,L79,D119,L97,U471,R817,U438,R157,U105,L219,U777,L965,U687,L906,D744,L983,D350,R664,D917,R431,D721,L153,U757,L665,U526,L49,U166,L59,D293,R962,D764,R538,U519,L24,U91,R11,U574,L647,U891,R44,D897,L715,U498,L624,D573,R287,U762,L613,D79,R122,U148,L849,D385,R792,D20,L512,D431,R818,U428,L10,D800,R773,D936,L594,D38,R824,D216,L220,U358,L463,U550,R968,D346,L658,U113,R813,U411,L730,D84,R479,U877,L730,D961,L839,D792,R424,U321,L105,D862,L815,D243,L521,D913,L1,D513,L269,U495,L27,U16,R904,D926,R640,U948,R346,D240,L273,U131,L296,U556,R347,D640,L261,D43,R136,U824,R126,U583,R736,U530,L734,U717,L256,U362,L86,U48,R851,U519,L610,D134,L554,D766,L179,U637,R71,D895,L21,D908,R486,D863,R31,U85,R420,D718,R466,D861,R655,D304,L701,D403,L860,D208,L595,U64,R999
+L992,D463,R10,D791,R312,D146,R865,D244,L364,D189,R35,U328,R857,D683,L660,D707,L908,D277,R356,U369,R197,D35,R625,D862,L769,U705,L728,U999,R938,U233,L595,U266,L697,U966,L536,D543,L669,D829,R910,U693,R753,D389,L647,U603,L660,D787,L138,D119,L131,D266,R268,D917,R776,U290,R920,U904,L46,D139,L341,D19,R982,U790,L981,U791,L147,U30,L246,U677,R343,D492,R398,D234,R76,D423,L709,D392,R741,U408,R878,U29,R446,U36,R806,U78,L76,D813,R584,U682,L187,U666,L340,D301,L694,U15,R800,U276,L755,U558,R366,D309,R571,U976,L286,D833,R318,U365,L864,U408,L352,D61,R284,D272,R240,D845,L206,U721,R367,D541,R628,U581,L750,D680,R695,D30,R849,U743,L214,U605,R533,U493,R803,D783,R168,U877,L61,D726,L794,D116,R717,U44,R964,U674,L291,D372,L381,D523,L644,U438,R983,D390,R520,D471,R556,D693,L919,D863,R84,D629,L264,D429,R82,U64,R835,D801,R93,U770,R441,D152,L718,D788,L797,U699,L82,U206,L40,U952,R902,U570,L759,D655,L131,D901,L470,D804,L407,U458,L922,D21,L171,U841,L237,D301,R192,D293,R984,U243,R846,U139,L413,U162,R925,D235,L115,U443,L884,D910,R335,U274,L338,U160,R125,D775,R824,D821,R531,D761,L189,U822,L602,D732,R473,U149,L128,U30,R77,D957,R811,D154,L988,D237,R425,D855,R482,D571,R134,D731,L905,U869,R916,D689,L17,U24,R353,D996,R832,U855,L76,U659,R581,D483,R821,D145,R199,D344,R487,D436,L92,U491,R365,D909,L17,D148,R307,U57,R666,U660,R195,D767,R612,D902,L594,D299,R670,D881,L583,D793,R58,U89,L99,D355,R394,D350,R920,U544,R887,U564,L238,U979,L565,D914,L95,U150,R292,U495,R506,U475,R813,D308,L797,D484,R9
--- a/src/day3.rs
+++ b/src/day3.rs
@ -0,0 +1,143 @@
+use std::io::BufRead;
+use std::str::FromStr;
+use std::num::ParseIntError;
+use std::fmt::{self, Display};
+use std::collections::HashSet;
+
+use Segment::*;
+
+#[derive(Debug, PartialEq)]
+enum Segment {
+    Up(i32),
+    Down(i32),
+    Right(i32),
+    Left(i32),
+}
+
+enum SegmentError {
+    UnknowDirection(char),
+    ParseIntError(ParseIntError)
+}
+
+impl Display for SegmentError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            SegmentError::UnknowDirection(direction) => write!(f, "Unknow direction `{}`", direction),
+            SegmentError::ParseIntError(ref e) => e.fmt(f),
+        }
+    }
+}
+
+impl FromStr for Segment {
+    type Err = SegmentError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let direction = s.chars().next().unwrap();
+        let length = s[1..].parse().map_err(|e| SegmentError::ParseIntError(e))?;
+
+        let segment = match direction {
+            'U' => Up(length),
+            'D' => Down(length),
+            'R' => Right(length),
+            'L' => Left(length),
+            direction => {
+                return Err(SegmentError::UnknowDirection(direction));
+            }
+        };
+        Ok(segment)
+    }
+}
+
+impl Segment {
+    #[inline]
+    fn direction(&self) -> (i32, i32) {
+        match self {
+            Up(_) => (0, 1),
+            Down(_) => (0, -1),
+            Right(_) => (1, 0),
+            Left(_) => (-1, 0),
+        }
+    }
+
+    #[inline]
+    fn length(&self) -> i32 {
+        match self {
+            Up(l) | Down(l) | Right(l) | Left(l) => *l
+        }
+    }
+}
+
+
+pub fn part1<F: BufRead> (mut input: F) {
+    let path1 = parse_input(&mut input);
+    let path2 = parse_input(&mut input);
+    let res = compute_closest_intersection(path1, path2);
+    println!("{}", res);
+}
+
+fn parse_input<F: BufRead> (input: &mut F) -> Vec<Segment> {
+    let mut buf = String::new();
+    let _num_bytes = input.read_line(&mut buf).expect("Unable to read a line of input file");
+    buf.trim().split(",").filter_map(|segment| segment.parse().ok()).collect()
+}
+
+fn compute_closest_intersection(path1: Vec<Segment>, path2: Vec<Segment>) -> i32 {
+    let seen1 = walk_on_path(path1, 0, (0, 0), HashSet::new());
+    let seen2 = walk_on_path(path2, 0, (0, 0), HashSet::new());
+
+    seen1.intersection(&seen2).map(|(x, y)| x.abs() + y.abs()).min().unwrap()
+
+}
+
+fn walk_on_path(
+    path: Vec<Segment>,
+    index: usize,
+    (x0, y0): (i32, i32),
+    mut seen: HashSet<(i32, i32)>
+) -> HashSet<(i32, i32)> {
+    if index == path.len() {
+        seen
+    } else {
+        let segment = &path[index];
+        let (dx, dy) = segment.direction();
+        let length = segment.length();
+        for i in 1..(length + 1) {
+            seen.insert((x0 + i * dx, y0 + i * dy));
+        }
+
+        walk_on_path(path, index + 1, (x0 + length * dx, y0 + length * dy), seen)
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use std::io;
+
+    #[test]
+    fn test_input_parsing() {
+        let mut input = io::Cursor::new(b"U7,R6,D4,L4\n");
+        let expected = vec![Up(7), Right(6), Down(4), Left(4)];
+
+        let res = parse_input(&mut input);
+        assert_eq!(res, expected);
+    }
+
+    #[test]
+    fn test_compute_closest_intersection() {
+        let mut input = r#"R8,U5,L5,D3
+U7,R6,D4,L4
+R75,D30,R83,U83,L12,D49,R71,U7,L72
+U62,R66,U55,R34,D71,R55,D58,R83
+R98,U47,R26,D63,R33,U87,L62,D20,R33,U53,R51
+U98,R91,D20,R16,D67,R40,U7,R15,U6,R7
+"#.as_bytes();
+        let test_results = [6, 159, 135];
+        for expected in &test_results {
+            let path1 = parse_input(&mut input);
+            let path2 = parse_input(&mut input);
+            let res = compute_closest_intersection(path1, path2);
+            assert_eq!(res, *expected)
+        }
+    }
+}
--- a/src/main.rs
+++ b/src/main.rs
@ -6,6 +6,7 @@ use std::io::BufReader;

 mod day1;
 mod day2;
+mod day3;

 fn main() {
    let matches = App::new("Advent of Code 2019")
@ -37,6 +38,7 @@ fn main() {
    let challenges = [
        day1::part1, day1::part2,
        day2::part1, day2::part2,
+        day3::part1,
    ];

    if let Some(f) = challenges.get(challenge) {