From 44afc3bbddadbec7b52eff4f4a52115c4940ac83 Mon Sep 17 00:00:00 2001
From: Antoine Martin <antoine@alarsyo.net>
Date: Sun, 5 Dec 2021 16:12:37 +0100
Subject: [PATCH] 2021: day05: part 1

---
 aoc2021/input/day05.txt          | 500 +++++++++++++++++++++++++++++++
 aoc2021/input/day05_provided.txt |  10 +
 aoc2021/src/day05.rs             | 108 +++++++
 aoc2021/src/lib.rs               |   1 +
 aoc2021/src/main.rs              |   3 +-
 5 files changed, 621 insertions(+), 1 deletion(-)
 create mode 100644 aoc2021/input/day05.txt
 create mode 100644 aoc2021/input/day05_provided.txt
 create mode 100644 aoc2021/src/day05.rs

diff --git a/aoc2021/input/day05.txt b/aoc2021/input/day05.txt
new file mode 100644
index 0000000..afd5d6f
--- /dev/null
+++ b/aoc2021/input/day05.txt
@@ -0,0 +1,500 @@
+964,133 -> 596,133
+920,215 -> 920,976
+123,528 -> 123,661
+613,13 -> 407,13
+373,876 -> 424,876
+616,326 -> 120,326
+486,335 -> 539,388
+104,947 -> 54,947
+319,241 -> 282,204
+453,175 -> 453,438
+485,187 -> 915,617
+863,605 -> 603,605
+870,524 -> 342,524
+967,395 -> 634,62
+405,181 -> 807,181
+961,363 -> 419,905
+89,586 -> 214,461
+545,481 -> 731,295
+407,678 -> 626,678
+421,642 -> 91,312
+11,22 -> 935,946
+770,208 -> 76,902
+668,858 -> 668,890
+568,451 -> 574,451
+233,56 -> 371,56
+233,932 -> 44,932
+404,81 -> 796,81
+520,77 -> 403,194
+296,736 -> 447,887
+210,909 -> 16,909
+692,483 -> 877,668
+777,289 -> 744,289
+22,760 -> 652,130
+96,360 -> 626,360
+101,267 -> 101,783
+47,667 -> 660,667
+805,682 -> 563,440
+112,15 -> 463,366
+406,808 -> 430,808
+793,767 -> 107,81
+560,534 -> 958,534
+722,429 -> 722,459
+646,889 -> 646,195
+433,942 -> 449,958
+716,503 -> 716,99
+266,450 -> 266,780
+316,81 -> 565,81
+760,452 -> 687,452
+976,983 -> 15,22
+499,564 -> 499,909
+839,913 -> 38,112
+707,333 -> 438,333
+47,644 -> 352,644
+807,309 -> 807,706
+434,686 -> 812,308
+559,572 -> 63,76
+493,352 -> 581,352
+94,88 -> 928,88
+898,738 -> 106,738
+201,10 -> 564,10
+976,914 -> 976,472
+836,153 -> 585,153
+178,43 -> 17,204
+784,967 -> 738,967
+370,359 -> 449,359
+13,526 -> 637,526
+399,158 -> 10,158
+572,293 -> 289,293
+627,674 -> 895,674
+921,402 -> 984,402
+907,667 -> 944,704
+574,877 -> 882,569
+977,977 -> 121,121
+550,584 -> 862,584
+396,556 -> 396,289
+391,33 -> 532,174
+12,988 -> 989,11
+48,787 -> 48,637
+476,638 -> 113,638
+985,985 -> 13,13
+838,784 -> 198,784
+567,195 -> 677,305
+174,251 -> 577,654
+296,801 -> 53,558
+983,899 -> 983,380
+507,230 -> 507,929
+264,516 -> 668,920
+865,952 -> 865,768
+522,290 -> 744,512
+936,958 -> 936,115
+527,871 -> 527,519
+944,972 -> 21,49
+880,380 -> 695,565
+471,374 -> 446,349
+503,597 -> 127,221
+471,514 -> 30,73
+890,232 -> 890,511
+14,461 -> 14,853
+167,676 -> 148,676
+987,230 -> 754,230
+797,725 -> 797,847
+347,21 -> 84,21
+839,274 -> 964,274
+607,456 -> 894,456
+335,949 -> 301,949
+167,236 -> 820,889
+87,558 -> 87,917
+318,788 -> 622,484
+699,583 -> 699,321
+971,967 -> 35,31
+420,44 -> 420,36
+29,484 -> 458,484
+768,157 -> 768,30
+690,839 -> 317,839
+870,578 -> 560,578
+697,195 -> 70,822
+689,45 -> 689,223
+790,724 -> 341,724
+694,291 -> 694,507
+43,339 -> 43,987
+590,733 -> 590,179
+751,361 -> 945,361
+99,820 -> 450,469
+460,696 -> 942,696
+783,940 -> 487,644
+630,537 -> 48,537
+643,856 -> 643,396
+558,733 -> 257,432
+16,972 -> 570,418
+636,188 -> 636,610
+868,138 -> 868,407
+85,424 -> 85,919
+710,932 -> 354,576
+356,505 -> 783,505
+606,876 -> 606,62
+577,431 -> 749,431
+108,262 -> 108,145
+615,455 -> 264,104
+205,754 -> 866,754
+189,182 -> 855,848
+10,43 -> 925,958
+293,773 -> 293,534
+746,313 -> 802,369
+607,174 -> 211,570
+860,840 -> 260,240
+879,78 -> 595,78
+11,143 -> 449,143
+190,983 -> 267,983
+912,92 -> 76,928
+744,364 -> 744,258
+436,417 -> 46,807
+629,592 -> 517,592
+113,893 -> 113,959
+714,213 -> 786,285
+868,165 -> 868,731
+349,69 -> 491,69
+278,430 -> 111,263
+593,849 -> 593,203
+156,860 -> 876,860
+169,615 -> 169,984
+983,93 -> 139,937
+94,548 -> 18,548
+623,72 -> 106,589
+530,334 -> 473,334
+384,746 -> 925,205
+711,74 -> 28,757
+850,728 -> 629,949
+378,801 -> 228,651
+347,968 -> 201,822
+82,578 -> 82,555
+149,405 -> 707,963
+254,169 -> 793,169
+443,454 -> 331,454
+460,659 -> 608,807
+838,807 -> 31,807
+561,952 -> 290,952
+755,626 -> 204,75
+550,424 -> 550,81
+772,115 -> 772,600
+40,517 -> 40,232
+277,841 -> 317,841
+899,150 -> 128,921
+735,332 -> 465,332
+839,254 -> 915,330
+959,616 -> 182,616
+729,723 -> 487,965
+64,838 -> 953,838
+689,830 -> 689,982
+191,83 -> 191,879
+522,833 -> 942,833
+877,785 -> 877,346
+255,95 -> 556,95
+782,491 -> 475,798
+268,815 -> 812,271
+119,181 -> 905,181
+445,457 -> 742,160
+973,30 -> 27,976
+356,681 -> 356,289
+882,279 -> 914,279
+672,162 -> 672,153
+180,729 -> 357,729
+985,716 -> 985,313
+191,618 -> 191,963
+949,749 -> 636,749
+289,902 -> 142,902
+923,615 -> 123,615
+710,929 -> 541,760
+211,402 -> 211,433
+515,178 -> 533,178
+525,869 -> 525,578
+201,569 -> 17,569
+629,848 -> 882,848
+152,512 -> 152,189
+914,723 -> 764,723
+218,231 -> 721,734
+438,382 -> 846,382
+582,475 -> 582,559
+529,943 -> 529,683
+330,312 -> 59,312
+242,900 -> 862,900
+271,220 -> 271,118
+182,459 -> 182,673
+513,265 -> 513,420
+918,942 -> 378,942
+277,765 -> 812,230
+625,874 -> 219,874
+737,533 -> 644,626
+647,975 -> 152,480
+638,284 -> 785,284
+549,680 -> 549,877
+886,278 -> 372,792
+130,560 -> 516,174
+186,741 -> 186,555
+208,536 -> 469,536
+674,906 -> 312,906
+934,156 -> 934,322
+568,412 -> 214,412
+243,19 -> 243,814
+861,230 -> 104,987
+683,891 -> 683,533
+545,740 -> 545,980
+343,320 -> 796,320
+821,220 -> 821,302
+578,741 -> 578,141
+633,405 -> 27,405
+645,975 -> 225,555
+25,527 -> 412,527
+378,817 -> 378,913
+352,741 -> 352,293
+48,986 -> 925,109
+506,231 -> 491,231
+854,883 -> 48,77
+261,221 -> 895,855
+902,240 -> 902,943
+145,338 -> 770,963
+832,216 -> 832,869
+480,385 -> 324,385
+644,202 -> 433,202
+202,176 -> 190,176
+668,693 -> 668,349
+95,230 -> 143,230
+873,144 -> 67,950
+232,509 -> 238,509
+963,43 -> 133,873
+527,631 -> 641,517
+363,61 -> 849,61
+72,326 -> 72,861
+542,801 -> 233,492
+247,48 -> 247,785
+972,563 -> 480,71
+362,870 -> 932,300
+263,811 -> 263,584
+556,157 -> 417,157
+946,900 -> 175,129
+790,542 -> 530,542
+777,195 -> 154,818
+71,764 -> 71,193
+197,13 -> 453,13
+664,714 -> 158,714
+257,819 -> 257,730
+796,927 -> 688,927
+124,53 -> 954,883
+30,16 -> 980,966
+84,151 -> 597,151
+840,776 -> 684,776
+548,460 -> 718,630
+291,635 -> 291,151
+948,43 -> 58,933
+373,483 -> 373,591
+309,81 -> 259,81
+692,808 -> 692,835
+737,112 -> 215,634
+808,595 -> 808,115
+160,912 -> 973,99
+494,191 -> 494,475
+713,925 -> 43,255
+736,580 -> 290,134
+257,679 -> 725,211
+464,81 -> 712,81
+35,147 -> 35,420
+372,159 -> 372,548
+508,228 -> 682,402
+120,491 -> 518,889
+139,948 -> 272,815
+398,523 -> 398,818
+935,50 -> 40,945
+415,959 -> 195,739
+250,868 -> 250,930
+77,60 -> 917,900
+584,389 -> 493,298
+362,163 -> 362,704
+670,740 -> 670,703
+689,297 -> 689,388
+988,572 -> 988,340
+238,248 -> 238,916
+748,753 -> 29,34
+184,565 -> 184,486
+812,217 -> 812,34
+60,140 -> 96,104
+826,673 -> 230,673
+221,221 -> 207,235
+449,483 -> 270,304
+805,810 -> 805,564
+952,52 -> 139,865
+428,967 -> 312,851
+854,673 -> 661,673
+985,209 -> 853,209
+523,365 -> 54,365
+492,171 -> 646,171
+908,853 -> 69,14
+38,698 -> 724,12
+400,479 -> 167,479
+948,313 -> 948,976
+280,145 -> 37,145
+206,858 -> 683,381
+203,413 -> 545,413
+726,173 -> 673,173
+30,954 -> 150,954
+319,592 -> 870,41
+808,91 -> 180,719
+845,612 -> 972,485
+160,430 -> 160,780
+19,339 -> 379,339
+476,550 -> 476,291
+341,785 -> 229,673
+371,476 -> 371,663
+509,836 -> 412,933
+980,20 -> 31,969
+822,526 -> 328,32
+859,314 -> 425,314
+963,961 -> 963,100
+984,978 -> 31,25
+659,251 -> 619,211
+649,477 -> 846,477
+32,259 -> 724,951
+468,753 -> 468,91
+690,301 -> 690,652
+436,912 -> 845,503
+32,123 -> 576,667
+142,79 -> 741,678
+610,228 -> 468,370
+172,667 -> 172,736
+961,700 -> 132,700
+804,875 -> 804,213
+71,970 -> 340,970
+171,52 -> 149,30
+754,604 -> 226,604
+485,941 -> 27,941
+126,383 -> 328,181
+41,39 -> 987,985
+128,62 -> 896,830
+414,278 -> 923,787
+712,15 -> 712,859
+794,35 -> 200,629
+516,147 -> 402,261
+526,862 -> 905,862
+721,407 -> 721,887
+728,920 -> 339,920
+117,417 -> 203,417
+291,561 -> 17,835
+171,359 -> 837,359
+93,125 -> 136,125
+220,226 -> 220,177
+75,434 -> 75,407
+235,664 -> 141,664
+553,490 -> 566,477
+487,651 -> 487,877
+699,150 -> 933,384
+73,556 -> 453,556
+363,371 -> 363,984
+905,106 -> 668,106
+139,271 -> 139,125
+466,379 -> 466,420
+12,935 -> 625,935
+89,892 -> 779,892
+119,701 -> 270,852
+354,886 -> 80,886
+917,376 -> 440,376
+23,182 -> 794,953
+451,718 -> 121,718
+62,251 -> 62,451
+642,74 -> 642,698
+425,200 -> 442,200
+828,175 -> 828,405
+751,743 -> 591,743
+569,681 -> 574,681
+329,187 -> 329,837
+302,592 -> 302,230
+359,135 -> 386,108
+44,234 -> 44,731
+836,305 -> 836,574
+170,512 -> 367,512
+576,699 -> 576,44
+398,185 -> 821,185
+733,78 -> 733,747
+141,183 -> 141,787
+65,360 -> 65,691
+828,780 -> 828,98
+776,744 -> 776,751
+881,74 -> 481,474
+438,642 -> 438,399
+676,972 -> 175,972
+60,318 -> 56,314
+312,169 -> 341,169
+736,472 -> 392,128
+225,281 -> 164,281
+407,799 -> 341,799
+458,826 -> 983,301
+12,988 -> 987,13
+23,854 -> 662,215
+82,863 -> 82,416
+542,708 -> 542,44
+659,51 -> 520,51
+353,246 -> 353,90
+985,976 -> 77,68
+628,493 -> 628,510
+51,48 -> 635,48
+97,814 -> 828,83
+14,44 -> 773,44
+603,178 -> 597,178
+11,220 -> 783,220
+613,39 -> 613,719
+68,303 -> 690,925
+121,974 -> 896,199
+343,54 -> 343,837
+744,303 -> 744,942
+678,370 -> 246,370
+937,134 -> 84,987
+357,333 -> 357,516
+848,212 -> 429,631
+909,244 -> 138,244
+122,794 -> 786,130
+274,611 -> 57,611
+66,337 -> 385,18
+847,356 -> 831,356
+740,480 -> 740,359
+194,443 -> 194,301
+50,564 -> 572,42
+86,587 -> 774,587
+708,258 -> 49,917
+420,530 -> 277,387
+509,580 -> 509,71
+237,196 -> 479,196
+442,287 -> 850,287
+830,393 -> 532,393
+274,720 -> 501,493
+610,565 -> 218,957
+380,393 -> 380,800
+237,847 -> 155,847
+267,791 -> 52,791
+275,772 -> 275,794
+239,238 -> 419,418
+200,785 -> 884,101
+185,980 -> 185,284
+47,46 -> 750,749
+724,661 -> 724,337
+630,349 -> 666,349
+21,911 -> 21,569
+661,562 -> 661,925
+41,898 -> 41,104
+988,67 -> 105,67
+739,65 -> 868,65
+187,973 -> 809,973
+730,211 -> 255,686
+254,445 -> 254,872
+622,364 -> 235,751
+402,980 -> 761,621
+46,488 -> 960,488
+799,708 -> 799,862
+909,181 -> 909,189
+450,266 -> 450,304
+631,584 -> 631,455
+164,830 -> 744,250
+679,755 -> 690,744
+949,26 -> 190,785
+695,783 -> 218,783
+269,151 -> 40,151
+166,152 -> 22,152
+281,819 -> 922,178
+956,649 -> 956,593
diff --git a/aoc2021/input/day05_provided.txt b/aoc2021/input/day05_provided.txt
new file mode 100644
index 0000000..b258f68
--- /dev/null
+++ b/aoc2021/input/day05_provided.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
diff --git a/aoc2021/src/day05.rs b/aoc2021/src/day05.rs
new file mode 100644
index 0000000..17ca76f
--- /dev/null
+++ b/aoc2021/src/day05.rs
@@ -0,0 +1,108 @@
+use std::collections::HashMap;
+use std::fmt::Write;
+use std::iter;
+
+use anyhow::{Context, Result};
+
+const INPUT: &str = include_str!("../input/day05.txt");
+
+pub fn run() -> Result<String> {
+    let mut res = String::with_capacity(128);
+
+    writeln!(res, "part 1: {}", part1(INPUT)?)?;
+
+    Ok(res)
+}
+
+fn part1(input: &str) -> Result<usize> {
+    let lines = input
+        .lines()
+        .map(str::parse::<Line>)
+        .collect::<Result<Vec<_>>>()?;
+
+    let mut grid = HashMap::new();
+
+    lines
+        .iter()
+        .filter(|l| l.is_horizontal() || l.is_vertical())
+        .for_each(|l| {
+            for cell in l.cells() {
+                *grid.entry(cell).or_insert(0) += 1;
+            }
+        });
+
+    Ok(grid.into_values().filter(|c| *c > 1).count())
+}
+
+#[derive(Debug)]
+struct Line {
+    from: (usize, usize),
+    to: (usize, usize),
+}
+
+impl Line {
+    fn is_horizontal(&self) -> bool {
+        self.to.1 == self.from.1
+    }
+
+    fn is_vertical(&self) -> bool {
+        self.to.0 == self.from.0
+    }
+
+    fn cells(&self) -> Box<dyn Iterator<Item = (usize, usize)>> {
+        if self.is_horizontal() {
+            let min = self.from.0.min(self.to.0);
+            let max = self.from.0.max(self.to.0);
+            Box::new((min..=max).zip(iter::repeat(self.from.1)))
+                as Box<dyn Iterator<Item = (usize, usize)>>
+        } else {
+            let min = self.from.1.min(self.to.1);
+            let max = self.from.1.max(self.to.1);
+            Box::new(iter::repeat(self.from.0).zip(min..=max))
+                as Box<dyn Iterator<Item = (usize, usize)>>
+        }
+    }
+}
+
+impl std::str::FromStr for Line {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self> {
+        let (from, to) = s
+            .split_once(" -> ")
+            .context("couldn't parse line: missing ` -> `")?;
+
+        let from = {
+            let (x, y) = from
+                .split_once(',')
+                .context("couldn't parse line origin: missing `,`")?;
+            (x.parse()?, y.parse()?)
+        };
+
+        let to = {
+            let (x, y) = to
+                .split_once(',')
+                .context("couldn't parse line origin: missing `,`")?;
+            (x.parse()?, y.parse()?)
+        };
+
+        Ok(Line { from, to })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const PROVIDED: &str = include_str!("../input/day05_provided.txt");
+
+    #[test]
+    fn part1_provided() {
+        assert_eq!(part1(PROVIDED).unwrap(), 5);
+    }
+
+    #[test]
+    fn part1_real() {
+        assert_eq!(part1(INPUT).unwrap(), 4745);
+    }
+}
diff --git a/aoc2021/src/lib.rs b/aoc2021/src/lib.rs
index 93675e3..e0126f6 100644
--- a/aoc2021/src/lib.rs
+++ b/aoc2021/src/lib.rs
@@ -4,3 +4,4 @@ pub mod day01;
 pub mod day02;
 pub mod day03;
 pub mod day04;
+pub mod day05;
diff --git a/aoc2021/src/main.rs b/aoc2021/src/main.rs
index e9fe9e3..20a1ce0 100644
--- a/aoc2021/src/main.rs
+++ b/aoc2021/src/main.rs
@@ -6,9 +6,10 @@ use aoc2021::day01;
 use aoc2021::day02;
 use aoc2021::day03;
 use aoc2021::day04;
+use aoc2021::day05;
 
 fn main() -> Result<()> {
-    let days: &[DayFunc] = &[day01::run, day02::run, day03::run, day04::run];
+    let days: &[DayFunc] = &[day01::run, day02::run, day03::run, day04::run, day05::run];
 
     aoc::run(days)
 }