Implement day 5

Nom is really nice and fast, why did I write parsers manually before.

.gitignore

@@ -59,3 +59,8 @@ target/
 
 # Rust lock
 *.lock
+
+# Performance data
+perf.data
+perf.data.old
+flamegraph.svg

2021/Cargo.toml

@@ -6,6 +6,7 @@ edition = "2021"
 
 [dependencies]
 clap = "3.0.0-beta.5"
+nom = "7"
 
 [profile.release]
 # Keep debug information in release for better flamegraphs

2021/inputs/05.txt

@@ -0,0 +1,500 @@
+781,721 -> 781,611
+334,551 -> 119,551
+25,153 -> 765,893
+588,619 -> 588,683
+167,63 -> 439,335
+340,129 -> 35,129
+578,712 -> 509,712
+855,426 -> 855,649
+778,71 -> 778,411
+21,314 -> 631,924
+552,148 -> 148,552
+531,889 -> 789,889
+85,963 -> 986,62
+914,140 -> 257,797
+520,721 -> 794,721
+49,936 -> 960,25
+458,941 -> 839,560
+113,797 -> 113,604
+554,136 -> 554,655
+112,208 -> 112,504
+78,410 -> 169,319
+176,148 -> 906,878
+56,98 -> 835,877
+538,981 -> 178,621
+553,102 -> 553,688
+452,761 -> 452,70
+487,574 -> 487,589
+356,406 -> 154,406
+11,646 -> 11,416
+543,19 -> 924,400
+862,773 -> 929,773
+292,901 -> 292,97
+985,236 -> 667,236
+745,572 -> 667,572
+752,794 -> 775,817
+269,649 -> 269,198
+928,327 -> 469,786
+284,937 -> 755,466
+308,876 -> 308,790
+201,94 -> 988,881
+233,958 -> 903,288
+210,879 -> 91,879
+760,48 -> 133,675
+55,79 -> 956,980
+988,15 -> 15,988
+25,974 -> 966,33
+903,671 -> 292,60
+587,770 -> 403,954
+83,379 -> 432,728
+30,121 -> 334,425
+375,516 -> 375,409
+72,370 -> 72,152
+575,595 -> 575,363
+248,64 -> 896,712
+703,421 -> 395,421
+66,978 -> 977,67
+450,961 -> 450,773
+830,895 -> 830,661
+373,58 -> 442,58
+739,383 -> 739,712
+510,188 -> 510,99
+350,880 -> 248,880
+771,278 -> 549,278
+266,434 -> 266,838
+315,490 -> 884,490
+360,651 -> 428,583
+333,452 -> 333,109
+313,414 -> 713,14
+23,982 -> 989,16
+196,201 -> 889,894
+485,761 -> 99,375
+288,918 -> 50,680
+912,206 -> 142,976
+242,10 -> 841,609
+972,11 -> 16,967
+859,142 -> 390,611
+48,348 -> 212,348
+246,514 -> 726,34
+29,754 -> 29,706
+617,296 -> 224,689
+671,487 -> 397,213
+913,898 -> 155,140
+437,688 -> 18,269
+150,150 -> 869,869
+386,873 -> 940,319
+57,326 -> 148,417
+847,12 -> 319,540
+741,640 -> 520,640
+111,458 -> 111,754
+595,615 -> 861,881
+244,722 -> 905,722
+323,394 -> 323,304
+560,562 -> 560,678
+48,750 -> 48,228
+80,40 -> 80,723
+730,839 -> 191,300
+300,773 -> 977,96
+619,892 -> 827,892
+22,226 -> 656,226
+125,968 -> 125,637
+116,923 -> 512,923
+59,741 -> 59,499
+484,930 -> 487,930
+362,175 -> 362,778
+960,986 -> 53,79
+170,748 -> 576,748
+810,291 -> 743,291
+761,924 -> 339,502
+730,850 -> 920,850
+778,949 -> 778,766
+254,724 -> 254,394
+685,177 -> 685,441
+442,290 -> 833,290
+181,209 -> 72,100
+91,924 -> 953,62
+318,880 -> 318,659
+570,632 -> 570,966
+955,227 -> 667,227
+439,666 -> 439,224
+276,385 -> 276,56
+544,521 -> 544,867
+187,626 -> 187,13
+307,235 -> 859,235
+759,416 -> 668,416
+357,882 -> 981,882
+651,71 -> 651,457
+615,711 -> 615,502
+474,162 -> 305,162
+320,33 -> 320,48
+799,420 -> 799,389
+448,46 -> 313,46
+925,141 -> 925,928
+332,101 -> 332,373
+41,948 -> 749,948
+276,672 -> 207,672
+315,736 -> 86,736
+844,688 -> 466,688
+357,199 -> 107,199
+902,950 -> 14,62
+277,251 -> 923,251
+963,38 -> 34,967
+71,389 -> 577,389
+712,911 -> 712,573
+186,976 -> 148,938
+407,389 -> 637,619
+917,118 -> 917,960
+988,571 -> 362,571
+845,941 -> 189,285
+686,537 -> 306,537
+915,929 -> 946,960
+447,30 -> 447,364
+832,833 -> 832,888
+957,953 -> 203,199
+982,73 -> 400,655
+159,704 -> 159,844
+284,347 -> 159,347
+903,280 -> 93,280
+769,961 -> 140,332
+899,145 -> 293,751
+850,643 -> 148,643
+580,870 -> 739,870
+686,250 -> 686,237
+142,528 -> 142,936
+827,224 -> 827,287
+972,946 -> 155,946
+706,851 -> 862,851
+564,231 -> 564,428
+511,662 -> 511,752
+838,842 -> 585,842
+60,871 -> 870,61
+719,824 -> 719,648
+183,232 -> 936,985
+131,56 -> 953,878
+406,952 -> 80,952
+884,518 -> 945,518
+427,439 -> 662,439
+829,920 -> 829,634
+966,262 -> 966,933
+813,27 -> 813,934
+784,101 -> 784,160
+744,313 -> 744,850
+969,213 -> 206,976
+957,56 -> 28,985
+312,620 -> 312,680
+454,131 -> 454,776
+360,174 -> 175,359
+711,114 -> 692,95
+452,839 -> 938,839
+641,56 -> 641,334
+566,890 -> 51,890
+869,109 -> 869,102
+119,36 -> 119,796
+301,583 -> 301,451
+733,603 -> 733,714
+718,703 -> 581,566
+709,513 -> 915,513
+405,13 -> 572,13
+782,26 -> 391,26
+15,74 -> 858,917
+975,978 -> 38,41
+11,316 -> 982,316
+303,367 -> 303,129
+847,143 -> 847,158
+856,687 -> 856,870
+715,524 -> 715,812
+451,288 -> 272,467
+576,179 -> 119,179
+10,623 -> 10,44
+652,631 -> 796,775
+930,613 -> 913,613
+803,746 -> 803,566
+306,602 -> 306,137
+582,491 -> 582,296
+181,116 -> 231,116
+802,646 -> 802,884
+75,623 -> 75,424
+370,680 -> 370,923
+806,497 -> 939,497
+301,331 -> 818,331
+912,916 -> 27,31
+24,82 -> 683,741
+862,205 -> 316,751
+245,842 -> 383,842
+544,946 -> 518,920
+129,192 -> 18,303
+831,915 -> 31,115
+306,824 -> 454,676
+851,341 -> 125,341
+790,154 -> 790,988
+407,586 -> 477,656
+144,988 -> 925,207
+264,391 -> 264,466
+901,651 -> 646,651
+865,936 -> 390,461
+631,737 -> 631,166
+103,939 -> 937,105
+505,813 -> 505,218
+260,457 -> 141,457
+52,762 -> 54,762
+26,95 -> 889,958
+638,41 -> 330,41
+612,775 -> 191,354
+863,224 -> 863,287
+674,87 -> 674,110
+189,76 -> 954,841
+372,483 -> 503,483
+166,75 -> 619,75
+938,983 -> 18,63
+442,573 -> 858,157
+681,590 -> 878,590
+276,465 -> 500,241
+644,703 -> 651,710
+848,363 -> 254,363
+204,109 -> 216,97
+81,529 -> 81,674
+74,44 -> 978,948
+929,237 -> 598,237
+298,644 -> 298,712
+678,367 -> 360,685
+413,27 -> 413,799
+684,403 -> 684,500
+188,601 -> 972,601
+33,257 -> 33,897
+278,299 -> 278,635
+261,983 -> 804,440
+216,324 -> 216,526
+399,332 -> 399,613
+826,702 -> 826,332
+137,203 -> 624,203
+326,552 -> 36,262
+142,927 -> 343,927
+21,330 -> 410,719
+721,768 -> 289,336
+807,715 -> 807,287
+775,678 -> 62,678
+771,10 -> 491,10
+287,829 -> 287,599
+589,947 -> 767,947
+160,348 -> 798,986
+699,264 -> 108,855
+605,145 -> 568,145
+264,615 -> 545,615
+633,111 -> 11,733
+589,886 -> 589,897
+728,839 -> 78,189
+739,924 -> 948,924
+140,354 -> 830,354
+619,662 -> 332,662
+592,960 -> 592,290
+510,908 -> 510,828
+792,518 -> 792,749
+148,20 -> 832,704
+529,837 -> 863,503
+802,371 -> 301,371
+682,429 -> 682,537
+885,918 -> 38,71
+590,229 -> 795,24
+782,704 -> 244,704
+936,71 -> 981,71
+27,272 -> 27,253
+558,48 -> 558,69
+661,422 -> 661,145
+152,335 -> 152,362
+516,407 -> 26,407
+449,731 -> 592,731
+187,456 -> 594,863
+145,290 -> 15,290
+667,213 -> 214,666
+660,872 -> 660,605
+649,617 -> 986,954
+86,914 -> 959,41
+895,967 -> 24,96
+40,154 -> 762,154
+27,106 -> 855,934
+929,913 -> 319,303
+749,314 -> 387,676
+76,380 -> 824,380
+632,329 -> 632,436
+154,496 -> 154,528
+127,958 -> 127,613
+592,606 -> 363,606
+929,228 -> 929,890
+832,596 -> 801,565
+824,978 -> 134,978
+638,485 -> 638,291
+783,848 -> 783,77
+646,877 -> 646,117
+461,279 -> 850,668
+300,450 -> 115,265
+916,205 -> 145,976
+510,760 -> 124,760
+884,668 -> 884,153
+285,370 -> 705,790
+845,42 -> 17,870
+784,59 -> 71,772
+627,268 -> 333,562
+731,403 -> 22,403
+980,43 -> 43,980
+16,988 -> 973,31
+720,881 -> 300,881
+23,182 -> 723,882
+129,887 -> 51,887
+186,934 -> 186,452
+114,815 -> 39,815
+868,777 -> 868,222
+554,218 -> 911,218
+247,408 -> 777,938
+391,69 -> 285,69
+239,472 -> 614,847
+422,918 -> 422,245
+852,905 -> 852,634
+631,164 -> 17,778
+987,988 -> 11,12
+435,891 -> 435,136
+564,409 -> 767,612
+611,508 -> 611,535
+744,965 -> 631,965
+308,604 -> 509,604
+77,250 -> 589,762
+505,950 -> 685,950
+907,222 -> 850,222
+700,674 -> 754,620
+238,294 -> 53,479
+875,130 -> 875,544
+368,547 -> 368,965
+618,206 -> 311,206
+127,972 -> 852,247
+561,192 -> 982,613
+573,399 -> 573,464
+311,109 -> 764,562
+69,813 -> 809,813
+195,594 -> 317,594
+900,467 -> 638,467
+806,810 -> 806,918
+451,17 -> 128,17
+93,837 -> 878,52
+299,726 -> 531,958
+968,984 -> 18,34
+957,38 -> 14,38
+283,583 -> 32,332
+922,822 -> 953,853
+589,466 -> 753,466
+203,791 -> 933,791
+122,739 -> 778,83
+294,658 -> 289,658
+365,200 -> 365,513
+611,941 -> 701,941
+927,111 -> 107,931
+754,529 -> 181,529
+364,933 -> 567,933
+717,960 -> 717,11
+612,472 -> 612,807
+971,252 -> 531,252
+88,911 -> 387,911
+885,837 -> 75,27
+222,289 -> 714,781
+754,40 -> 293,501
+866,517 -> 949,517
+858,586 -> 331,586
+157,21 -> 731,595
+173,216 -> 822,865
+353,206 -> 353,318
+68,88 -> 957,88
+370,645 -> 200,815
+981,83 -> 89,975
+259,112 -> 259,435
+184,920 -> 825,279
+252,357 -> 252,56
+722,349 -> 368,703
+928,973 -> 597,973
+677,656 -> 788,545
+222,766 -> 527,461
+870,787 -> 972,889
+11,986 -> 986,11
+163,918 -> 748,333
+111,75 -> 823,75
+603,250 -> 375,478
+338,582 -> 338,454
+372,179 -> 452,179
+571,96 -> 571,723
+243,460 -> 267,460
+850,63 -> 43,870
+837,863 -> 113,139
+21,886 -> 709,198
+154,650 -> 181,650
+320,506 -> 320,706
+983,722 -> 983,657
+830,225 -> 190,865
+924,12 -> 11,925
+838,827 -> 258,247
+690,792 -> 690,582
+465,658 -> 146,977
+790,935 -> 39,184
+318,627 -> 318,125
+245,939 -> 291,939
+803,219 -> 254,768
+262,476 -> 441,476
+790,225 -> 790,372
+250,722 -> 613,722
+368,326 -> 368,474
+148,666 -> 394,912
+813,588 -> 238,13
+84,323 -> 84,957
+566,716 -> 822,716
+794,633 -> 459,633
+355,634 -> 237,634
+950,755 -> 950,867
+292,696 -> 340,696
+121,391 -> 361,631
+58,516 -> 624,516
+859,37 -> 184,712
+686,819 -> 428,819
+11,12 -> 988,989
+718,679 -> 280,679
+515,524 -> 515,664
+136,459 -> 136,56
+703,763 -> 703,858
+290,733 -> 290,33
+910,928 -> 910,21
+570,937 -> 570,808
+462,215 -> 462,747
+388,181 -> 712,505
+933,705 -> 933,601
+605,492 -> 188,492
+737,818 -> 564,818
+214,629 -> 735,108
+139,942 -> 598,942
+708,187 -> 541,187
+646,611 -> 325,611
+788,356 -> 718,426
+267,250 -> 267,930
+94,819 -> 94,191
+661,537 -> 661,363
+464,290 -> 471,297
+656,68 -> 337,68
+31,515 -> 797,515
+876,21 -> 81,21
+630,932 -> 21,323
+259,58 -> 542,58
+703,523 -> 703,949
+470,310 -> 470,20
+69,983 -> 977,75
+569,908 -> 569,931
+645,718 -> 645,665
+819,371 -> 819,705
+772,709 -> 772,736
+330,870 -> 382,818
+982,317 -> 982,778
+626,411 -> 626,887
+466,33 -> 466,635
+519,939 -> 519,131
+402,253 -> 402,300
+180,712 -> 826,66
+55,764 -> 941,764
+659,859 -> 659,944
+346,374 -> 346,500
+880,333 -> 880,767
+42,969 -> 983,28
+363,688 -> 363,148
+645,880 -> 265,500

2021/src/common.rs

@@ -60,3 +60,12 @@ impl<'a, I: FromStr> Iterator for LineParser<'a, I> {
         self.iter.next()?.parse().ok()
     }
 }
+
+/// Return two arguments in their natural PartialOrd order
+pub fn ordered<O: PartialOrd>(a: O, b: O) -> (O, O) {
+    if a < b {
+        (a, b)
+    } else {
+        (b, a)
+    }
+}

2021/src/day05.rs

@@ -1,9 +1,99 @@
+use std::collections::HashMap;
 use std::io::Read;
+use std::iter::repeat;
 
-pub fn part1(_input: &mut dyn Read) -> String {
-    todo!()
+use nom::bytes::complete::tag;
+use nom::sequence::tuple;
+use nom::Finish;
+use nom::IResult;
+
+use crate::common::ordered;
+use crate::common::LineIter;
+
+type Coord = (u16, u16);
+
+fn coordinates(input: &str) -> IResult<&str, Coord> {
+    use nom::character::complete;
+
+    let (input, (x, _, y)) = tuple((complete::u16, complete::char(','), complete::u16))(input)?;
+
+    Ok((input, (x, y)))
 }
 
-pub fn part2(_input: &mut dyn Read) -> String {
-    todo!()
+fn line_definition(input: &str) -> IResult<&str, (Coord, Coord)> {
+    let (input, (begin, _, end)) = tuple((coordinates, tag(" -> "), coordinates))(input)?;
+
+    // Sorting the coordinates saves trouble later
+    Ok((input, ordered(begin, end)))
+}
+
+fn stripe(
+    map: &mut HashMap<Coord, u16>,
+    xs: impl Iterator<Item = u16>,
+    ys: impl Iterator<Item = u16>,
+) {
+    for (x, y) in xs.zip(ys) {
+        *map.entry((x, y)).or_default() += 1;
+    }
+}
+
+fn part_common(input: &mut dyn Read, diagonals: bool) -> String {
+    let mut reader = LineIter::new(input);
+    let mut map = HashMap::new();
+
+    while let Some(line) = reader.next() {
+        let (begin, end) = line_definition(line).finish().unwrap().1;
+
+        if begin.0 == end.0 {
+            let y_range = begin.1..=end.1;
+            stripe(&mut map, repeat(begin.0), y_range);
+        } else if begin.1 == end.1 {
+            let x_range = begin.0..=end.0;
+            stripe(&mut map, x_range, repeat(begin.1));
+        } else if diagonals {
+            let x_range = begin.0..=end.0;
+            let y_range = (begin.1.min(end.1))..=(begin.1.max(end.1));
+
+            if begin.1 > end.1 {
+                // For a downward slope we need to reverse Y
+                stripe(&mut map, x_range, y_range.rev());
+            } else {
+                stripe(&mut map, x_range, y_range);
+            }
+        }
+    }
+
+    map.values().filter(|&&v| v > 1).count().to_string()
+}
+
+pub fn part1(input: &mut dyn Read) -> String {
+    part_common(input, false)
+}
+
+pub fn part2(input: &mut dyn Read) -> String {
+    part_common(input, true)
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::test_implementation;
+
+    use super::*;
+
+    const SAMPLE: &[u8] = include_bytes!("samples/05.txt");
+
+    #[test]
+    fn test_parser() {
+        assert_eq!(line_definition("6,4 -> 2,0"), Ok(("", ((2, 0), (6, 4)))));
+    }
+
+    #[test]
+    fn sample_part1() {
+        test_implementation(part1, SAMPLE, 5)
+    }
+
+    #[test]
+    fn sample_part2() {
+        test_implementation(part2, SAMPLE, 12)
+    }
 }

2021/src/samples/05.txt

@@ -0,0 +1,10 @@
+0,9 -> 5,9
+8,0 -> 0,8
+9,4 -> 3,4
+2,2 -> 2,1
+7,0 -> 7,4
+6,4 -> 2,0
+0,9 -> 2,9
+3,4 -> 1,4
+0,0 -> 8,8
+5,5 -> 8,2