day5

day5.rkt

@@ -0,0 +1,59 @@
+#lang racket
+
+(define (map-map f lst) ; map . map
+  (map (λ (x) (map (λ (y) (f y)) x)) lst))
+
+(define/match (add-dx-dy points)
+  [((list (list x1 y1) (list x2 y2)))
+   (let* ([dx (- x2 x1)]
+          [dy (- y2 y1)]
+          [len (max (abs dx) (abs dy))])
+     (list (list x1 y1) (list x2 y2) dx dy len))])
+
+(define (vectorize line)
+  (let* ([parts (string-split line " -> ")] ; '("0,9 -> 5,9") -> '("0,9" "5,9")
+         [strings (map (λ (part) (string-split part ",")) parts)] ; '("0,9" "5,9") -> '(("0" "9") ("5" "9"))
+         [nums (map-map string->number strings)] ; '(("0" "9") ("5" "9")) -> '((0 9) (5 9))
+         [vectors (add-dx-dy nums)]) ; '((x1 y2) (x2 y2) dx dy length)
+    vectors))
+
+(define/match (non-diagonal? vect)
+  [((list _ _ dx dy _)) (or (= dx 0) (= dy 0))])
+
+(define/match (get-points-from-vect vect) ; takes vect '((x1 y1) (x2 y2) dx dy len) and returns a list of points it hits '((x1 y1) (x2 y2) ..)
+  [((list (list x1 y1) (list x2 y2) dx dy len))
+   (let loop ([i len])
+     (if (= i 0) ; at the end
+         (list (list x1 y1)) ; return this point
+         (append (list (list (+ x1 (/ (* dx i) len)) (+ y1 (/ (* dy i) len)))) ; return the next point..
+                 (loop (sub1 i)))))]) ; appended to the result of recursing with i - 1
+
+(define (add-point ht point)
+  (let ([dups (hash-ref ht point 0)])
+    (hash-set! ht point (+ 1 dups))))
+
+(define (travel-and-add ht vects)
+  (for ([i (in-list vects)])
+    (let ([points (get-points-from-vect i)])
+      (map (λ (p) (add-point ht p)) points))))
+
+(define part1
+  (let* ([lines (file->lines "day5.txt")]
+         [vectors (map vectorize lines)]
+         [non-diagonals (filter non-diagonal? vectors)]
+         [ht (make-hash)]
+         [points-hit (travel-and-add ht non-diagonals)]
+         [counts (hash-values ht)])
+         (length (filter (λ (x) (> x 1)) counts))))
+
+part1
+
+(define part2
+  (let* ([lines (file->lines "day5.txt")]
+         [vectors (map vectorize lines)]
+         [ht (make-hash)]
+         [points-hit (travel-and-add ht vectors)]
+         [counts (hash-values ht)])
+         (length (filter (λ (x) (> x 1)) counts))))
+
+part2

day5.test.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

day5.txt

@@ -0,0 +1,500 @@
+348,742 -> 620,742
+494,864 -> 494,484
+193,136 -> 301,136
+342,692 -> 342,538
+234,525 -> 102,393
+72,964 -> 847,189
+639,430 -> 99,970
+398,791 -> 398,187
+181,144 -> 205,168
+607,617 -> 416,617
+98,339 -> 98,437
+763,119 -> 176,119
+450,848 -> 450,664
+293,133 -> 293,98
+308,98 -> 308,15
+157,21 -> 405,269
+792,471 -> 409,471
+42,955 -> 956,41
+895,269 -> 895,884
+629,635 -> 392,635
+169,23 -> 273,127
+250,847 -> 250,665
+709,56 -> 709,626
+938,599 -> 669,868
+913,46 -> 458,501
+844,417 -> 844,424
+178,651 -> 640,189
+226,266 -> 149,266
+654,421 -> 654,499
+368,780 -> 368,38
+183,743 -> 497,429
+942,34 -> 387,589
+987,461 -> 987,348
+485,275 -> 330,275
+33,460 -> 456,883
+606,304 -> 606,628
+755,170 -> 755,187
+342,862 -> 250,954
+866,125 -> 151,840
+795,489 -> 599,685
+905,525 -> 905,457
+99,620 -> 99,339
+899,507 -> 699,707
+627,444 -> 923,444
+798,80 -> 419,459
+580,237 -> 580,907
+947,336 -> 947,727
+491,466 -> 546,411
+335,221 -> 458,221
+547,70 -> 407,210
+520,80 -> 647,80
+835,58 -> 835,300
+574,239 -> 589,239
+219,670 -> 219,22
+512,69 -> 255,69
+83,701 -> 239,701
+874,109 -> 48,935
+980,892 -> 159,71
+154,879 -> 53,879
+782,37 -> 89,730
+481,736 -> 481,614
+377,886 -> 569,694
+777,403 -> 726,454
+728,952 -> 728,972
+495,643 -> 879,643
+425,564 -> 187,326
+443,110 -> 386,167
+529,279 -> 529,103
+985,983 -> 16,14
+145,112 -> 877,844
+914,34 -> 121,827
+409,229 -> 784,229
+719,86 -> 479,86
+929,984 -> 218,984
+985,928 -> 299,242
+168,159 -> 168,743
+189,784 -> 189,498
+401,58 -> 390,58
+47,283 -> 452,688
+246,292 -> 246,461
+869,901 -> 643,675
+879,593 -> 108,593
+707,417 -> 336,417
+99,401 -> 99,502
+583,764 -> 583,668
+493,934 -> 493,78
+643,570 -> 643,990
+278,765 -> 600,443
+940,437 -> 940,488
+812,896 -> 812,594
+727,711 -> 25,711
+173,586 -> 667,92
+169,879 -> 466,582
+361,650 -> 361,276
+725,818 -> 725,662
+48,119 -> 781,852
+921,62 -> 921,647
+135,613 -> 135,295
+702,969 -> 194,461
+306,709 -> 274,709
+117,182 -> 117,856
+608,635 -> 608,854
+448,250 -> 448,641
+635,552 -> 341,552
+528,432 -> 51,432
+711,763 -> 987,487
+43,931 -> 917,57
+980,841 -> 526,387
+279,412 -> 377,412
+334,107 -> 509,282
+164,15 -> 164,345
+708,139 -> 708,846
+323,930 -> 323,282
+256,902 -> 922,236
+586,453 -> 244,111
+21,92 -> 840,911
+282,888 -> 839,331
+278,439 -> 712,873
+110,595 -> 696,595
+95,531 -> 804,531
+800,206 -> 800,881
+396,244 -> 396,441
+334,60 -> 122,60
+640,331 -> 640,467
+757,126 -> 731,126
+430,245 -> 932,245
+160,655 -> 753,62
+502,432 -> 751,432
+434,378 -> 434,287
+907,374 -> 552,729
+548,864 -> 632,864
+616,961 -> 746,831
+116,316 -> 666,866
+78,44 -> 950,916
+873,570 -> 355,570
+202,859 -> 885,176
+449,348 -> 904,348
+143,179 -> 760,796
+478,823 -> 478,55
+790,446 -> 790,257
+34,888 -> 736,888
+630,696 -> 437,889
+350,589 -> 118,821
+803,373 -> 808,373
+490,778 -> 818,450
+487,725 -> 487,836
+794,502 -> 794,114
+136,743 -> 136,634
+572,103 -> 194,103
+488,614 -> 528,614
+18,878 -> 539,357
+889,35 -> 889,271
+436,419 -> 21,419
+422,319 -> 422,821
+176,935 -> 923,188
+398,398 -> 436,436
+327,45 -> 820,538
+643,428 -> 890,675
+743,714 -> 143,114
+203,359 -> 189,359
+346,672 -> 346,190
+263,804 -> 263,249
+93,683 -> 93,453
+19,180 -> 238,399
+47,941 -> 888,100
+525,888 -> 236,599
+624,397 -> 126,397
+382,119 -> 382,981
+972,753 -> 336,117
+682,978 -> 48,344
+639,477 -> 639,408
+545,966 -> 12,966
+275,234 -> 401,234
+912,20 -> 101,20
+54,109 -> 809,864
+242,149 -> 242,283
+664,353 -> 828,353
+117,539 -> 26,630
+794,554 -> 624,554
+828,536 -> 43,536
+746,717 -> 746,420
+540,930 -> 224,930
+862,229 -> 862,212
+492,917 -> 835,574
+960,496 -> 960,618
+148,530 -> 148,485
+415,974 -> 494,974
+694,118 -> 654,158
+672,210 -> 672,81
+548,692 -> 668,812
+891,50 -> 10,931
+639,652 -> 844,652
+579,522 -> 556,545
+231,880 -> 170,880
+443,12 -> 443,775
+562,185 -> 562,984
+619,313 -> 74,858
+371,502 -> 642,231
+969,694 -> 714,949
+943,157 -> 179,921
+821,305 -> 821,427
+782,579 -> 874,671
+378,943 -> 378,956
+315,636 -> 572,893
+544,357 -> 315,357
+51,158 -> 16,158
+151,428 -> 508,428
+818,939 -> 90,939
+99,396 -> 451,396
+602,834 -> 695,834
+974,145 -> 974,919
+327,630 -> 254,630
+858,166 -> 900,166
+537,681 -> 564,681
+672,674 -> 672,619
+544,408 -> 750,614
+84,664 -> 210,664
+204,886 -> 469,886
+475,940 -> 475,592
+868,922 -> 614,922
+987,939 -> 367,939
+854,498 -> 956,498
+863,148 -> 22,989
+565,580 -> 948,197
+231,952 -> 798,385
+935,832 -> 113,10
+631,362 -> 631,329
+405,143 -> 303,143
+807,831 -> 891,831
+450,976 -> 450,247
+488,676 -> 508,676
+170,328 -> 636,794
+626,815 -> 626,938
+217,558 -> 708,558
+598,549 -> 532,549
+824,307 -> 304,307
+539,932 -> 390,932
+542,786 -> 435,893
+735,42 -> 389,388
+677,448 -> 65,448
+929,915 -> 29,15
+870,344 -> 870,287
+187,138 -> 754,138
+729,353 -> 508,132
+919,821 -> 317,219
+272,459 -> 272,72
+599,413 -> 342,413
+919,862 -> 199,142
+229,476 -> 893,476
+438,516 -> 150,228
+914,132 -> 173,873
+905,815 -> 315,815
+766,136 -> 766,207
+548,546 -> 451,643
+836,231 -> 381,231
+484,854 -> 852,854
+736,209 -> 307,209
+751,156 -> 809,156
+659,937 -> 659,333
+74,899 -> 485,488
+843,329 -> 843,584
+793,944 -> 910,827
+67,298 -> 610,841
+43,15 -> 960,932
+633,527 -> 912,806
+782,246 -> 716,312
+30,46 -> 912,928
+473,833 -> 473,189
+903,506 -> 61,506
+85,404 -> 85,898
+944,682 -> 944,465
+420,695 -> 391,666
+560,110 -> 810,360
+246,368 -> 25,368
+399,397 -> 781,15
+452,618 -> 452,340
+467,854 -> 890,854
+77,314 -> 77,780
+523,501 -> 523,646
+67,284 -> 637,284
+88,13 -> 988,913
+173,20 -> 844,691
+667,821 -> 722,821
+384,840 -> 792,432
+270,36 -> 270,352
+311,16 -> 311,334
+736,900 -> 736,264
+613,827 -> 748,962
+41,81 -> 885,925
+408,884 -> 756,884
+380,612 -> 402,634
+82,645 -> 82,708
+934,331 -> 316,331
+634,116 -> 634,891
+942,56 -> 942,642
+441,260 -> 955,774
+925,980 -> 314,369
+317,893 -> 577,893
+362,137 -> 433,137
+434,928 -> 434,623
+819,18 -> 819,488
+185,348 -> 615,778
+895,357 -> 492,357
+742,645 -> 742,151
+522,855 -> 366,699
+867,390 -> 57,390
+95,566 -> 389,272
+887,793 -> 887,871
+351,251 -> 351,30
+309,448 -> 865,448
+190,690 -> 70,570
+383,805 -> 383,607
+140,157 -> 140,164
+685,222 -> 705,222
+192,949 -> 192,358
+856,768 -> 856,967
+337,344 -> 771,344
+919,86 -> 53,952
+137,723 -> 887,723
+33,108 -> 873,948
+195,690 -> 195,184
+136,505 -> 136,520
+509,69 -> 509,800
+255,742 -> 255,740
+650,105 -> 650,483
+985,451 -> 268,451
+68,346 -> 171,346
+472,28 -> 574,28
+660,308 -> 660,382
+341,553 -> 341,419
+430,304 -> 807,304
+333,258 -> 795,258
+853,637 -> 252,36
+881,893 -> 237,249
+552,160 -> 826,160
+728,446 -> 728,905
+529,326 -> 529,860
+564,759 -> 564,737
+533,688 -> 78,233
+445,314 -> 329,198
+935,597 -> 652,597
+955,958 -> 174,177
+178,522 -> 178,457
+124,351 -> 74,351
+265,840 -> 451,654
+771,914 -> 771,332
+72,14 -> 72,574
+970,828 -> 197,55
+631,744 -> 631,746
+765,759 -> 119,113
+260,882 -> 262,882
+676,760 -> 61,145
+680,168 -> 959,168
+466,811 -> 466,745
+566,242 -> 566,471
+768,975 -> 768,75
+391,550 -> 391,591
+781,678 -> 771,678
+731,620 -> 951,620
+973,290 -> 973,664
+838,691 -> 835,691
+294,240 -> 378,240
+390,708 -> 908,190
+521,933 -> 963,933
+358,46 -> 919,46
+431,410 -> 431,297
+833,706 -> 330,706
+13,910 -> 876,910
+619,567 -> 619,398
+165,779 -> 165,941
+21,139 -> 21,535
+921,420 -> 358,420
+629,111 -> 608,111
+654,244 -> 654,500
+982,386 -> 982,841
+252,127 -> 144,235
+144,518 -> 144,344
+581,589 -> 130,138
+927,835 -> 882,790
+859,658 -> 320,119
+110,326 -> 110,168
+149,64 -> 917,832
+651,771 -> 897,771
+788,66 -> 231,623
+710,608 -> 370,268
+927,175 -> 778,26
+957,970 -> 53,66
+350,313 -> 350,192
+115,505 -> 129,505
+414,163 -> 182,163
+874,334 -> 532,676
+441,790 -> 441,976
+66,162 -> 226,162
+839,453 -> 310,982
+63,974 -> 132,974
+51,383 -> 297,137
+343,954 -> 262,873
+726,474 -> 637,563
+449,205 -> 449,279
+855,845 -> 722,845
+28,750 -> 33,750
+272,175 -> 212,235
+428,172 -> 710,172
+824,834 -> 824,557
+25,864 -> 855,34
+66,425 -> 84,425
+456,812 -> 456,785
+286,294 -> 73,294
+400,329 -> 525,204
+888,160 -> 888,124
+879,742 -> 761,742
+893,751 -> 858,786
+621,765 -> 10,154
+162,280 -> 162,889
+96,830 -> 646,280
+646,720 -> 250,324
+367,586 -> 695,258
+298,353 -> 566,621
+813,256 -> 813,367
+559,672 -> 471,672
+951,187 -> 234,904
+868,753 -> 80,753
+91,937 -> 803,225
+112,142 -> 18,236
+936,281 -> 936,976
+95,867 -> 753,209
+421,735 -> 833,735
+830,755 -> 963,755
+355,272 -> 355,70
+309,479 -> 309,45
+951,145 -> 676,145
+513,143 -> 713,143
+491,565 -> 988,68
+797,742 -> 596,541
+581,621 -> 277,317
+132,480 -> 101,480
+140,72 -> 375,72
+524,221 -> 897,594
+694,549 -> 179,34
+689,729 -> 689,527
+27,953 -> 27,32
+913,774 -> 913,705
+669,861 -> 669,360
+454,250 -> 454,344
+863,95 -> 13,945
+341,50 -> 341,795
+863,50 -> 212,50
+73,689 -> 143,689
+944,20 -> 31,933
+22,988 -> 873,137
+798,552 -> 798,774
+935,583 -> 935,393
+462,176 -> 986,176
+739,400 -> 972,400
+441,31 -> 441,37
+628,381 -> 628,339
+545,345 -> 615,345
+91,736 -> 373,736
+825,738 -> 825,687
+541,877 -> 541,569
+750,739 -> 390,739
+873,384 -> 873,665
+597,61 -> 385,61
+518,62 -> 229,62
+623,192 -> 502,192
+163,861 -> 732,292
+748,304 -> 873,429
+375,436 -> 375,655
+146,228 -> 146,91
+808,844 -> 243,844
+174,115 -> 982,923
+598,384 -> 598,956
+932,736 -> 843,736
+772,110 -> 883,110
+298,960 -> 852,406
+744,772 -> 693,823
+605,639 -> 731,639
+126,770 -> 732,164
+13,986 -> 988,11
+756,37 -> 756,164
+132,900 -> 984,48
+806,524 -> 331,524
+84,645 -> 84,195
+329,447 -> 939,447
+684,566 -> 793,566
+747,595 -> 747,181
+293,121 -> 430,121
+42,918 -> 826,918
+32,312 -> 833,312
+42,309 -> 42,752
+332,74 -> 736,74
+699,209 -> 495,209
+297,113 -> 297,827
+515,973 -> 515,35
+774,951 -> 774,290
+471,921 -> 919,921
+297,282 -> 297,524
+477,825 -> 477,343
+220,665 -> 351,796
+483,128 -> 376,128