5 files changed, 615 insertions, 0 deletions

diff --git a/2021/day5/Cargo.toml b/2021/day5/Cargo.toml
new file mode 100644
index 0000000..f9b62bf
--- /dev/null
+++ b/2021/day5/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "day5"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/2021/day5/input b/2021/day5/input
new file mode 100644
index 0000000..45eb5f4
--- /dev/null
+++ b/2021/day5/input
@@ -0,0 +1,500 @@
+957,596 -> 957,182
+763,144 -> 69,144
+761,794 -> 911,944
+510,440 -> 147,440
+859,33 -> 859,409
+602,518 -> 748,518
+980,545 -> 676,241
+60,528 -> 616,528
+37,242 -> 37,892
+216,966 -> 216,120
+372,910 -> 372,307
+688,864 -> 94,864
+691,17 -> 167,17
+989,928 -> 989,816
+207,84 -> 982,84
+890,714 -> 502,326
+286,329 -> 686,329
+959,62 -> 460,62
+840,82 -> 780,82
+960,12 -> 14,958
+418,45 -> 983,610
+318,264 -> 988,934
+458,11 -> 861,11
+805,197 -> 380,622
+261,907 -> 261,734
+409,617 -> 826,617
+285,457 -> 759,931
+104,241 -> 913,241
+781,141 -> 781,671
+48,956 -> 348,956
+921,517 -> 974,517
+565,621 -> 724,621
+381,276 -> 381,59
+82,25 -> 946,25
+978,16 -> 17,977
+850,438 -> 125,438
+313,850 -> 313,195
+789,963 -> 789,29
+110,156 -> 241,156
+925,974 -> 458,974
+93,153 -> 696,756
+748,312 -> 120,312
+566,367 -> 360,367
+687,295 -> 687,284
+219,925 -> 180,925
+59,952 -> 59,140
+641,333 -> 361,53
+158,587 -> 158,96
+857,278 -> 857,195
+653,45 -> 34,664
+639,384 -> 814,384
+67,24 -> 902,859
+850,278 -> 850,448
+342,505 -> 342,287
+504,924 -> 536,956
+408,666 -> 408,310
+747,347 -> 747,176
+766,468 -> 54,468
+283,905 -> 283,421
+476,334 -> 476,59
+490,935 -> 753,672
+385,772 -> 940,772
+907,316 -> 853,370
+144,717 -> 746,115
+741,819 -> 230,819
+524,397 -> 524,237
+411,824 -> 288,824
+160,719 -> 744,135
+252,550 -> 440,738
+902,64 -> 902,422
+392,194 -> 955,757
+937,735 -> 937,446
+292,49 -> 985,49
+899,464 -> 481,46
+304,369 -> 648,369
+247,723 -> 247,697
+665,941 -> 185,461
+548,25 -> 446,127
+663,558 -> 154,558
+52,47 -> 872,867
+983,68 -> 983,795
+492,705 -> 654,867
+82,888 -> 33,888
+550,443 -> 229,764
+868,508 -> 375,15
+120,829 -> 652,829
+787,296 -> 814,296
+705,643 -> 351,643
+52,23 -> 558,23
+390,92 -> 390,393
+713,520 -> 897,520
+280,481 -> 827,481
+599,181 -> 599,235
+483,140 -> 773,140
+571,227 -> 571,779
+830,45 -> 830,745
+617,745 -> 449,745
+89,176 -> 841,928
+358,868 -> 906,320
+897,669 -> 654,669
+717,729 -> 123,135
+305,330 -> 305,598
+220,964 -> 600,964
+607,715 -> 492,715
+837,561 -> 820,561
+542,38 -> 542,118
+390,970 -> 915,445
+343,160 -> 475,160
+163,60 -> 972,869
+786,500 -> 946,500
+401,393 -> 401,910
+336,962 -> 528,962
+520,489 -> 520,525
+558,584 -> 363,584
+786,880 -> 584,678
+704,435 -> 153,986
+356,522 -> 235,643
+225,67 -> 229,71
+389,381 -> 55,47
+918,229 -> 332,229
+558,989 -> 558,370
+307,821 -> 307,447
+13,232 -> 742,961
+659,809 -> 467,809
+905,942 -> 456,942
+234,810 -> 234,497
+421,287 -> 643,65
+183,164 -> 312,164
+652,955 -> 977,630
+157,820 -> 853,124
+278,480 -> 278,384
+504,399 -> 298,605
+955,76 -> 798,76
+565,352 -> 109,352
+912,16 -> 66,862
+972,786 -> 235,49
+146,15 -> 146,186
+944,149 -> 497,596
+485,84 -> 762,84
+975,983 -> 16,24
+11,896 -> 887,20
+826,924 -> 126,224
+246,648 -> 158,736
+773,377 -> 582,377
+296,947 -> 378,865
+592,291 -> 592,861
+331,470 -> 16,470
+239,85 -> 705,85
+409,842 -> 409,966
+145,438 -> 145,340
+239,859 -> 239,409
+651,508 -> 314,845
+720,39 -> 176,583
+762,444 -> 762,29
+983,962 -> 60,39
+745,248 -> 91,902
+990,18 -> 990,503
+441,472 -> 441,211
+524,837 -> 248,561
+160,215 -> 842,897
+469,544 -> 989,544
+311,241 -> 103,33
+887,610 -> 746,610
+377,942 -> 377,803
+920,401 -> 823,401
+10,142 -> 10,486
+850,955 -> 850,578
+887,728 -> 887,678
+555,749 -> 84,749
+839,620 -> 32,620
+432,709 -> 432,183
+312,164 -> 859,711
+20,119 -> 739,838
+930,871 -> 324,265
+41,702 -> 41,520
+48,210 -> 794,956
+479,526 -> 479,123
+364,739 -> 364,379
+920,969 -> 73,122
+382,314 -> 382,604
+969,877 -> 129,37
+274,893 -> 52,671
+696,296 -> 696,221
+469,735 -> 626,892
+682,435 -> 682,937
+626,550 -> 626,604
+898,904 -> 898,755
+836,849 -> 445,458
+405,237 -> 405,724
+253,74 -> 908,729
+837,802 -> 597,802
+375,450 -> 316,450
+621,784 -> 314,784
+856,136 -> 188,804
+983,11 -> 29,965
+82,134 -> 752,134
+677,299 -> 573,299
+43,726 -> 43,304
+886,629 -> 886,603
+439,471 -> 74,836
+973,879 -> 122,28
+550,246 -> 497,246
+49,109 -> 816,876
+294,493 -> 271,493
+495,397 -> 495,342
+846,892 -> 881,927
+267,397 -> 72,592
+670,168 -> 22,816
+482,302 -> 482,681
+309,692 -> 453,692
+597,369 -> 597,589
+518,475 -> 633,475
+391,484 -> 493,382
+177,135 -> 139,135
+458,17 -> 825,17
+514,292 -> 272,50
+410,734 -> 142,734
+465,975 -> 542,898
+32,901 -> 346,587
+390,478 -> 571,659
+835,839 -> 189,839
+769,407 -> 769,788
+974,40 -> 103,911
+710,709 -> 246,709
+468,857 -> 343,982
+777,552 -> 951,552
+23,490 -> 346,490
+270,384 -> 855,384
+386,454 -> 166,454
+166,388 -> 319,388
+698,514 -> 698,180
+554,162 -> 528,162
+651,363 -> 879,363
+327,123 -> 327,255
+439,492 -> 719,212
+903,438 -> 903,356
+99,611 -> 99,552
+512,652 -> 45,185
+565,284 -> 565,180
+81,710 -> 637,154
+321,769 -> 164,769
+32,307 -> 32,204
+310,338 -> 310,914
+239,691 -> 357,691
+573,164 -> 559,164
+887,961 -> 693,767
+362,904 -> 362,944
+467,294 -> 236,294
+182,53 -> 182,264
+19,950 -> 951,18
+191,575 -> 440,824
+192,168 -> 690,666
+538,552 -> 891,905
+243,38 -> 243,403
+417,140 -> 417,818
+894,45 -> 726,213
+245,898 -> 245,527
+567,946 -> 567,983
+572,675 -> 363,675
+318,618 -> 735,618
+616,580 -> 981,580
+37,881 -> 134,881
+624,675 -> 271,322
+323,686 -> 770,686
+93,385 -> 626,385
+715,382 -> 862,382
+170,342 -> 170,84
+747,221 -> 380,221
+981,311 -> 981,577
+372,186 -> 372,826
+961,91 -> 130,922
+48,603 -> 48,110
+34,975 -> 935,74
+707,18 -> 707,192
+261,149 -> 41,369
+35,589 -> 35,247
+544,522 -> 437,522
+797,712 -> 346,712
+622,47 -> 78,591
+642,390 -> 642,414
+793,29 -> 69,29
+978,905 -> 978,296
+212,515 -> 212,920
+835,166 -> 68,933
+168,742 -> 168,720
+390,276 -> 666,276
+507,792 -> 987,792
+895,242 -> 895,402
+121,950 -> 943,128
+303,336 -> 303,205
+293,390 -> 293,736
+433,963 -> 433,867
+824,327 -> 620,531
+553,689 -> 867,689
+226,984 -> 226,284
+153,308 -> 173,308
+855,959 -> 345,959
+830,895 -> 830,981
+557,63 -> 557,205
+51,857 -> 328,857
+224,243 -> 224,517
+830,773 -> 830,520
+607,210 -> 782,385
+876,330 -> 327,330
+985,11 -> 18,978
+352,936 -> 111,936
+900,39 -> 986,39
+10,626 -> 10,795
+369,942 -> 11,942
+136,770 -> 654,252
+209,541 -> 209,557
+69,671 -> 848,671
+811,451 -> 194,451
+149,46 -> 850,747
+704,386 -> 704,953
+117,346 -> 387,346
+238,701 -> 688,251
+789,220 -> 789,815
+967,512 -> 967,213
+641,652 -> 151,162
+91,942 -> 312,942
+42,226 -> 801,985
+166,37 -> 603,37
+854,976 -> 951,976
+392,23 -> 772,23
+299,196 -> 299,288
+514,560 -> 844,890
+618,699 -> 348,429
+604,947 -> 604,735
+189,851 -> 407,633
+907,719 -> 907,449
+167,421 -> 864,421
+491,383 -> 538,383
+939,504 -> 939,433
+78,649 -> 78,975
+817,246 -> 322,741
+395,195 -> 205,195
+872,275 -> 872,500
+196,621 -> 280,621
+634,619 -> 634,422
+395,30 -> 395,232
+895,628 -> 619,904
+58,66 -> 186,194
+626,477 -> 708,559
+747,712 -> 747,28
+935,798 -> 220,798
+459,530 -> 704,530
+648,679 -> 79,110
+778,135 -> 778,66
+657,352 -> 906,352
+499,160 -> 615,160
+830,226 -> 830,489
+364,971 -> 826,971
+879,923 -> 543,923
+914,984 -> 612,984
+594,810 -> 508,810
+55,467 -> 269,253
+360,478 -> 360,902
+176,890 -> 176,431
+867,121 -> 16,972
+728,876 -> 65,213
+606,112 -> 842,112
+563,532 -> 914,532
+783,139 -> 369,139
+564,359 -> 846,359
+79,326 -> 15,390
+972,419 -> 972,35
+686,839 -> 755,839
+427,856 -> 77,856
+102,410 -> 925,410
+468,177 -> 901,610
+865,249 -> 930,314
+784,447 -> 863,368
+684,708 -> 223,708
+555,228 -> 555,900
+380,600 -> 222,600
+900,408 -> 188,408
+773,677 -> 773,16
+560,287 -> 560,790
+130,851 -> 959,22
+338,951 -> 626,663
+678,726 -> 405,726
+243,469 -> 243,276
+783,486 -> 66,486
+469,536 -> 469,770
+689,148 -> 689,340
+396,689 -> 396,673
+848,759 -> 848,770
+965,775 -> 965,605
+889,907 -> 284,302
+161,169 -> 942,950
+619,267 -> 394,492
+323,786 -> 18,481
+953,643 -> 884,643
+371,446 -> 371,252
+890,915 -> 192,217
+674,259 -> 674,247
+877,479 -> 877,117
+620,843 -> 620,734
+597,722 -> 597,939
+935,663 -> 935,469
+108,844 -> 108,596
+211,447 -> 211,482
+123,657 -> 721,59
+774,858 -> 774,86
+978,500 -> 978,305
+152,890 -> 937,105
+728,356 -> 728,261
+354,373 -> 433,452
+586,627 -> 586,949
+764,381 -> 735,410
+986,899 -> 199,112
+251,418 -> 251,596
+897,379 -> 897,388
+149,901 -> 253,901
+650,229 -> 46,229
+446,707 -> 446,44
+953,898 -> 697,898
+772,422 -> 762,432
+608,756 -> 927,756
+138,911 -> 716,333
+414,583 -> 244,583
+219,267 -> 219,751
+69,746 -> 69,886
+444,243 -> 493,194
+604,950 -> 244,950
+450,198 -> 31,617
+918,852 -> 109,43
+967,800 -> 267,100
+388,516 -> 760,516
+656,954 -> 513,954
+80,680 -> 80,44
+360,848 -> 360,800
+10,10 -> 989,989
+889,927 -> 104,142
+882,187 -> 812,187
+416,522 -> 356,522
+797,795 -> 273,271
+175,371 -> 12,371
+726,595 -> 956,595
+852,355 -> 852,357
+959,83 -> 338,83
+822,766 -> 140,84
+968,129 -> 181,916
+17,28 -> 975,986
+15,913 -> 624,304
+589,322 -> 468,443
+894,21 -> 309,606
+83,25 -> 963,905
+143,380 -> 377,146
+587,151 -> 507,151
+257,967 -> 257,882
+770,552 -> 770,573
+128,90 -> 886,848
+456,953 -> 456,669
+930,434 -> 668,434
+501,835 -> 796,540
+36,980 -> 989,27
+494,690 -> 626,690
+105,945 -> 972,78
+409,730 -> 409,62
+901,160 -> 831,90
+881,490 -> 28,490
+736,244 -> 38,942
+295,770 -> 199,770
+866,416 -> 808,416
+875,716 -> 875,189
+763,393 -> 241,915
+583,237 -> 704,237
+29,153 -> 637,153
+767,282 -> 767,107
+456,242 -> 456,165
+455,232 -> 749,232
+54,128 -> 766,840
+901,73 -> 939,73
+928,118 -> 854,118
+15,983 -> 975,23
+600,92 -> 260,92
+247,714 -> 247,490
+511,332 -> 19,824
+55,15 -> 968,928
+246,29 -> 25,29
+22,101 -> 761,840
+876,177 -> 139,914
+165,150 -> 822,807
+258,707 -> 773,707
+68,788 -> 68,875
+858,142 -> 758,142
+719,642 -> 810,642
+928,904 -> 928,338
+287,977 -> 978,286
+883,13 -> 883,31
+681,301 -> 681,957
+762,863 -> 405,506
+194,657 -> 733,118
+78,41 -> 497,41
+840,627 -> 840,168
+335,54 -> 335,822
+136,983 -> 526,593
+120,156 -> 120,630
diff --git a/2021/day5/input.example b/2021/day5/input.example
new file mode 100644
index 0000000..b258f68
--- /dev/null
+++ b/2021/day5/input.example
@@ -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/2021/day5/input.mini.example b/2021/day5/input.mini.example
new file mode 100644
index 0000000..b775b12
--- /dev/null
+++ b/2021/day5/input.mini.example
@@ -0,0 +1,2 @@
+1,1 -> 3,3
+9,7 -> 7,9
diff --git a/2021/day5/src/main.rs b/2021/day5/src/main.rs
new file mode 100644
index 0000000..498deb0
--- /dev/null
+++ b/2021/day5/src/main.rs
@@ -0,0 +1,95 @@
+use std::cmp::{max, min};
+use std::collections::HashMap;
+use std::env;
+use std::fs::File;
+use std::io::{BufRead, BufReader};
+
+fn main() {
+    let reader = open_file();
+
+    let mut coords: HashMap<(i32, i32), i32> = HashMap::new();
+
+    for line in reader.lines() {
+        if let Ok(line) = line {
+            let vents = line.split(" -> ").collect::<Vec<&str>>();
+            let first = vents[0].split(",").collect::<Vec<&str>>();
+            let second = vents[1].split(",").collect::<Vec<&str>>();
+
+            let first: Vec<i32> = first.into_iter().map(|s| s.parse().unwrap()).collect();
+            let second: Vec<i32> = second.into_iter().map(|s| s.parse().unwrap()).collect();
+
+            let xstep: i32;
+            let ystep: i32;
+            let start_x = min(first[0], second[0]);
+            let end_x = max(first[0], second[0]);
+            let start_y = min(first[1], second[1]);
+            let end_y = max(first[1], second[1]);
+            let distance = max(end_x - start_x, end_y - start_y);
+
+            if first[0] > second[0] {
+                xstep = -1;
+            } else if first[0] < second[0] {
+                xstep = 1;
+            } else {
+                xstep = 0;
+            }
+
+            if first[1] > second[1] {
+                ystep = -1;
+            } else if first[1] < second[1] {
+                ystep = 1;
+            } else {
+                ystep = 0;
+            }
+
+            for step in 0..=distance {
+                let counter = coords
+                    .entry((first[0] + step * xstep, first[1] + step * ystep))
+                    .or_insert(0);
+                *counter += 1;
+            }
+        }
+    }
+
+    // println!("coords: {:?}", coords);
+    // visualize(&coords);
+
+    let result = coords.iter().filter(|(_, &y)| y >= 2).count();
+    println!("{}", result);
+}
+
+fn visualize(map: &HashMap<(i32, i32), i32>) {
+    let start_x = map.iter().map(|((x, _), _)| x).min().unwrap();
+    let start_y = map.iter().map(|((_, y), _)| y).min().unwrap();
+    let end_x = map.iter().map(|((x, _), _)| x).max().unwrap();
+    let end_y = map.iter().map(|((_, y), _)| y).max().unwrap();
+    println!("start_x: {}", start_x);
+    println!("start_y: {}", start_y);
+    println!("end_x: {}", end_x);
+    println!("end_y: {}", end_y);
+
+    for y in *start_y..=*end_y {
+        for x in *start_x..=*end_x {
+            if let Some(val) = map.get(&(x, y)) {
+                print!("{}", val);
+            } else {
+                print!(".")
+            }
+        }
+        println!("");
+    }
+}
+
+fn open_file() -> BufReader<File> {
+    let args: Vec<String> = env::args().collect();
+
+    if args.len() != 2 {
+        eprintln!("Usage: {} <filename>", args[0]);
+        std::process::exit(1);
+    }
+
+    let filename = &args[1];
+
+    let file = File::open(filename).unwrap_or_else(|_| panic!("No such file: {}", filename));
+    BufReader::new(file)
+}