2021 solutions

2021/01.rkt

@@ -0,0 +1,20 @@
+#lang br
+(require racket/file rackunit)
+
+(define depths (map string->number (file->lines "01.rktd")))
+
+(define (positive-deltas depths)
+  (filter positive?
+          (for/list ([d1 (in-list depths)]
+                     [d2 (in-list (cdr depths))])
+            (- d2 d1))))
+
+(check-equal? (length (positive-deltas depths)) 1167)
+
+(define (trios depths)
+  (for/list ([d1 (in-list depths)]
+             [d2 (in-list (cdr depths))]
+             [d3 (in-list (cddr depths))])
+    (+ d1 d2 d3)))
+
+(check-equal? (length (positive-deltas (trios depths))) 1130)

2021/02.rkt

@@ -0,0 +1,32 @@
+#lang br
+(require racket/file sugar/list rackunit)
+
+(define instructions
+  (slice-at (for/list ([datum (in-port read (open-input-file "02.rktd"))])
+              datum) 2))
+
+(define (solve matcher)
+  (for/fold ([pos 0]
+             [depth 0]
+             [aim 0]
+             #:result (* pos depth))
+            ([i (in-list instructions)])
+    (matcher pos depth aim i)))
+
+(define (solve-1)
+  (solve (λ (pos depth aim i)
+           (match i
+             [(list 'forward amt) (values (+ pos amt) depth aim)]
+             [(list 'down amt) (values pos (+ depth amt) aim)]
+             [(list 'up amt) (values pos (- depth amt) aim)]))))
+
+(check-equal? (solve-1) 1488669)
+
+(define (solve-2)
+  (solve (λ (pos depth aim i)
+           (match i
+             [(list 'forward amt) (values (+ pos amt) (+ depth (* aim amt)) aim)]
+             [(list 'down amt) (values pos depth (+ aim amt))]
+             [(list 'up amt) (values pos depth (- aim amt))]))))
+
+(check-equal? (solve-2) 1176514794)

2021/03.rkt

@@ -0,0 +1,40 @@
+#lang br
+(require racket/file rackunit)
+
+(define lines (map string->list (file->lines "03.rktd")))
+(define (digit-columns lines) (apply map list lines))
+
+(define (most-common-digit chars)
+  (define zeroes (count (λ (c) (char=? c #\0)) chars))
+  (define most-threshold (/ (length chars) 2))
+  (cond
+    [(= zeroes most-threshold) #f]
+    [(> zeroes most-threshold) #\0]
+    [else #\1]))
+
+(define (least-common-digit chars)
+  (match (most-common-digit chars)
+    [#false #false]
+    [#\0 #\1]
+    [_ #\0]))
+
+(define (chars->binary-number chars)
+  (string->number (list->string chars) 2))
+
+(define gamma-rate (chars->binary-number (map most-common-digit (digit-columns lines))))
+(define epsilon-rate (chars->binary-number (map least-common-digit (digit-columns lines))))
+
+(check-equal? (* gamma-rate epsilon-rate) 4174964)
+
+(define (find-digit proc default)
+    (for/fold ([lines lines]
+             #:result (chars->binary-number (car lines)))
+            ([i (in-range (length (car lines)))]
+             #:break (= (length lines) 1))
+    (define target (or (proc (list-ref (digit-columns lines) i)) default))
+    (filter (λ (line) (char=? (list-ref line i) target)) lines)))
+
+(define oxygen-rate (find-digit most-common-digit #\1))
+(define co2-rate (find-digit least-common-digit #\0))
+
+(check-equal? (* oxygen-rate co2-rate) 4474944)

2021/04.rkt

@@ -0,0 +1,43 @@
+#lang br
+(require racket/file sugar rackunit)
+
+(define lines (file->lines "04.rktd"))
+
+(define numbers-to-draw (map string->number (string-split (string-replace (car lines) "," " "))))
+
+(define boards
+  (map list->vector (slice-at (map string->number (string-split (string-join (cdr lines)))) 25)))
+
+(define winning-lines
+  (let ()
+    (define rows '((0 1 2 3 4) (5 6 7 8 9) (10 11 12 13 14) (15 16 17 18 19) (20 21 22 23 24)))
+    (define cols (apply map list rows))
+    (append rows cols)))
+
+(define (board-wins board)
+  (for/or ([winning-line winning-lines])
+    (for/and ([idx winning-line])
+      (eq? (vector-ref board idx) #true))))
+
+(define (run-game boards)
+  (for*/fold ([boards boards]
+              [winners null]
+              #:result (reverse winners))
+             ([number numbers-to-draw]
+              #:break (empty? boards))
+    (for ([board boards])
+      (define pos-of-number (vector-member number board))
+      (when pos-of-number
+        (vector-set! board pos-of-number #true)))
+    (define-values (new-winners losers) (partition board-wins boards))
+    (values losers (append (for/list ([winner new-winners])
+                             (cons number winner)) winners))))
+
+(define (calc-score res)
+  (match res
+    [(cons last-number board) (* last-number (apply + (filter number? (vector->list board))))]))
+
+(define results (run-game boards))
+(check-equal? (calc-score (first results)) 64084)
+(check-equal? (calc-score (last results)) 12833)
+

2021/04.rktd

@@ -0,0 +1,601 @@
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+
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2021/05.rkt

@@ -0,0 +1,38 @@
+#lang br
+(require racket/file sugar rackunit racket/set)
+
+(define lines (map (λ (s) (map (λ (s2) (define ints (map string->number (string-split s2 ",")))
+                                 (+ (first ints) (* +i (second ints)))) (string-split s " -> "))) (file->lines "05.rktd")))
+
+(define (Line-not-diagonal line)
+  (match line
+    [(list left right) (or (= (real-part left) (real-part right)) (= (imag-part left) (imag-part right)))]))
+
+;; why does make-polar cause the solution to run faster?
+;; both functions create an imaginary number
+;; make-polar is slower to create the numbers (because it has to call trig functions)
+;; but storing the polar numbers with frequency-hash is much faster
+;; using inexact coefficients makes make-rectangular go faster
+;; but still not as fast as make-polar
+(define go-fast? #true)
+(define imag-func (if go-fast? make-polar make-rectangular))
+
+(define (expand line)
+  (match-define (list x1 x2) (map real-part line))
+  (match-define (list y1 y2) (map imag-part line))
+  (cond
+    [(= x1 x2)
+     (for/list ([i (in-range (apply min (list y1 y2)) (add1 (apply max (list y1 y2))))])
+       (imag-func x1 i))]
+    [(= y1 y2)
+     (for/list ([i (in-range (apply min (list x1 x2)) (add1 (apply max (list x1 x2))))])
+       (imag-func i y1))]
+    [else (for/list ([x (in-range x1 ((if (> x1 x2) sub1 add1) x2) (if (> x1 x2) -1 1))]
+                     [y (in-range y1 ((if (> y1 y2) sub1 add1) y2) (if (> y1 y2) -1 1))])
+            (imag-func x y))]))
+
+(define (calc-result points)
+  (length (filter (λ (x) (>= x 2)) (hash-values (time (frequency-hash points))))))
+
+(check-equal? (calc-result (append-map expand (filter Line-not-diagonal lines))) 6113)
+(check-equal? (calc-result (append-map expand lines)) 20373)

2021/05.rktd

@@ -0,0 +1,500 @@
+309,347 -> 309,464
+425,687 -> 300,687
+226,766 -> 885,107
+681,618 -> 921,378
+968,54 -> 38,984
+35,341 -> 321,627
+493,485 -> 632,485
+908,183 -> 110,981
+677,378 -> 677,231
+703,378 -> 703,536
+179,581 -> 429,331
+339,133 -> 664,458
+212,680 -> 212,136
+251,699 -> 858,699
+163,725 -> 163,22
+70,226 -> 97,226
+968,119 -> 954,119
+551,551 -> 415,551
+768,167 -> 546,167
+125,302 -> 155,332
+640,201 -> 341,201
+757,791 -> 757,736
+406,570 -> 418,558
+250,919 -> 976,193
+570,362 -> 304,96
+463,973 -> 463,337
+322,199 -> 322,73
+141,186 -> 141,906
+964,940 -> 964,743
+99,461 -> 15,461
+255,856 -> 255,194
+650,293 -> 650,136
+89,98 -> 969,978
+974,977 -> 37,40
+641,795 -> 985,795
+441,972 -> 441,427
+18,942 -> 943,17
+166,167 -> 617,167
+182,146 -> 790,146
+88,854 -> 928,14
+537,38 -> 233,38
+786,562 -> 867,562
+251,102 -> 147,102
+551,373 -> 672,252
+915,713 -> 791,589
+28,373 -> 28,651
+463,365 -> 396,365
+349,948 -> 737,948
+246,860 -> 84,860
+334,817 -> 866,285
+880,958 -> 641,719
+229,203 -> 740,714
+39,220 -> 575,756
+899,383 -> 275,383
+49,952 -> 774,952
+384,42 -> 581,42
+11,731 -> 522,731
+194,638 -> 679,153
+922,279 -> 922,398
+589,579 -> 709,579
+97,716 -> 244,716
+769,923 -> 769,189
+636,567 -> 866,337
+413,925 -> 729,925
+581,524 -> 89,32
+970,217 -> 851,217
+716,373 -> 122,967
+606,785 -> 191,785
+322,432 -> 706,432
+788,911 -> 788,889
+904,917 -> 904,862
+889,351 -> 796,351
+508,18 -> 508,165
+859,187 -> 879,187
+531,409 -> 562,378
+914,97 -> 233,778
+194,191 -> 194,592
+620,674 -> 55,109
+194,973 -> 863,973
+679,940 -> 679,296
+836,108 -> 700,108
+861,376 -> 585,376
+166,299 -> 166,141
+847,377 -> 847,217
+872,972 -> 872,413
+28,872 -> 28,695
+876,152 -> 108,920
+487,536 -> 697,536
+30,28 -> 982,980
+834,503 -> 834,586
+927,459 -> 339,459
+87,809 -> 770,126
+24,973 -> 981,16
+185,383 -> 185,13
+850,328 -> 541,19
+399,111 -> 742,111
+703,305 -> 458,305
+571,889 -> 803,657
+356,697 -> 364,697
+847,160 -> 108,899
+170,954 -> 137,954
+927,120 -> 897,150
+687,662 -> 507,662
+762,259 -> 762,951
+90,612 -> 647,55
+114,437 -> 483,68
+138,269 -> 638,269
+720,947 -> 29,947
+563,52 -> 360,52
+665,953 -> 187,475
+283,855 -> 283,744
+120,284 -> 120,319
+935,422 -> 349,422
+372,858 -> 372,779
+68,768 -> 814,22
+206,400 -> 22,400
+72,954 -> 977,49
+861,557 -> 794,557
+893,654 -> 893,132
+306,364 -> 697,364
+828,165 -> 695,165
+122,57 -> 986,921
+509,470 -> 608,470
+794,730 -> 520,456
+291,305 -> 525,71
+648,530 -> 92,530
+329,173 -> 329,343
+960,941 -> 133,114
+256,523 -> 369,523
+433,379 -> 195,379
+199,783 -> 821,783
+974,205 -> 299,205
+200,400 -> 27,573
+294,175 -> 294,493
+320,20 -> 320,393
+274,85 -> 969,780
+112,73 -> 112,969
+371,381 -> 121,631
+942,906 -> 46,906
+663,742 -> 208,287
+422,258 -> 422,356
+884,283 -> 859,283
+750,142 -> 710,142
+823,454 -> 642,273
+296,366 -> 296,245
+518,615 -> 852,949
+74,513 -> 655,513
+850,77 -> 850,950
+985,980 -> 33,28
+16,982 -> 979,19
+265,234 -> 849,234
+303,408 -> 229,334
+344,63 -> 932,651
+417,597 -> 548,597
+729,361 -> 245,845
+888,156 -> 80,964
+215,29 -> 411,225
+762,108 -> 115,108
+63,855 -> 875,43
+398,382 -> 874,858
+419,78 -> 419,417
+263,553 -> 131,553
+766,399 -> 584,399
+778,126 -> 226,678
+580,781 -> 580,401
+623,506 -> 966,506
+364,723 -> 364,349
+834,667 -> 177,10
+402,515 -> 402,493
+924,50 -> 22,952
+64,826 -> 64,470
+199,694 -> 145,694
+893,900 -> 20,27
+850,834 -> 725,959
+47,573 -> 575,45
+71,287 -> 71,296
+796,728 -> 796,442
+88,700 -> 726,700
+230,332 -> 412,514
+618,284 -> 618,661
+221,738 -> 817,142
+149,38 -> 474,38
+563,331 -> 441,331
+219,187 -> 522,187
+300,341 -> 300,633
+228,305 -> 70,463
+396,875 -> 22,875
+533,116 -> 519,116
+257,781 -> 257,443
+181,236 -> 181,822
+10,13 -> 986,989
+59,290 -> 753,984
+121,89 -> 121,827
+958,233 -> 653,233
+685,641 -> 685,322
+167,124 -> 446,403
+246,170 -> 77,339
+503,189 -> 503,72
+666,182 -> 824,340
+825,675 -> 629,479
+967,915 -> 967,785
+749,403 -> 92,403
+950,217 -> 950,391
+356,872 -> 514,872
+279,900 -> 138,900
+114,284 -> 502,672
+700,792 -> 32,124
+252,783 -> 806,229
+557,215 -> 557,103
+35,29 -> 963,957
+650,285 -> 23,912
+669,191 -> 446,414
+66,283 -> 66,37
+564,250 -> 175,250
+425,611 -> 425,964
+662,224 -> 707,224
+599,979 -> 599,873
+402,886 -> 402,979
+329,181 -> 329,964
+120,891 -> 685,326
+788,438 -> 788,460
+140,939 -> 338,939
+496,343 -> 327,343
+749,151 -> 749,339
+181,527 -> 181,455
+61,949 -> 966,44
+138,262 -> 894,262
+192,146 -> 801,146
+301,405 -> 765,405
+938,235 -> 938,55
+543,958 -> 320,958
+54,982 -> 867,169
+66,147 -> 702,783
+839,419 -> 97,419
+519,879 -> 519,707
+159,255 -> 159,787
+258,897 -> 968,897
+427,10 -> 427,62
+782,750 -> 782,960
+878,742 -> 785,649
+171,74 -> 883,74
+220,184 -> 910,874
+696,984 -> 696,512
+175,753 -> 303,753
+666,515 -> 45,515
+886,101 -> 14,973
+121,823 -> 154,823
+63,976 -> 987,52
+480,478 -> 167,791
+757,338 -> 757,719
+593,286 -> 542,286
+989,602 -> 989,135
+793,857 -> 712,857
+65,976 -> 843,198
+729,334 -> 106,957
+102,234 -> 42,294
+830,223 -> 267,223
+800,590 -> 921,590
+526,38 -> 863,38
+770,719 -> 65,14
+317,267 -> 541,267
+653,697 -> 653,720
+506,532 -> 483,555
+564,387 -> 205,387
+971,669 -> 971,966
+421,905 -> 421,264
+506,85 -> 407,85
+435,863 -> 230,863
+945,133 -> 694,133
+604,921 -> 604,168
+66,677 -> 499,244
+300,551 -> 893,551
+836,228 -> 836,631
+29,208 -> 443,208
+546,584 -> 148,584
+855,904 -> 855,315
+636,694 -> 852,478
+399,252 -> 399,170
+46,596 -> 46,789
+919,211 -> 201,929
+662,983 -> 545,866
+22,913 -> 908,27
+441,605 -> 94,952
+190,257 -> 769,836
+700,395 -> 861,556
+562,620 -> 562,687
+34,165 -> 603,734
+372,302 -> 585,302
+71,857 -> 588,340
+956,566 -> 738,784
+778,610 -> 74,610
+331,640 -> 346,655
+274,473 -> 274,691
+646,142 -> 144,142
+911,971 -> 618,971
+233,341 -> 233,505
+467,990 -> 41,990
+633,739 -> 57,163
+585,405 -> 905,405
+320,449 -> 320,628
+44,738 -> 44,293
+67,267 -> 770,970
+933,155 -> 765,323
+383,879 -> 896,366
+130,986 -> 435,986
+264,863 -> 979,148
+114,721 -> 725,110
+546,949 -> 546,790
+762,42 -> 67,42
+443,985 -> 245,985
+689,803 -> 126,803
+496,702 -> 943,255
+955,963 -> 117,125
+686,411 -> 979,704
+226,256 -> 226,352
+889,683 -> 889,437
+47,161 -> 545,161
+450,283 -> 450,469
+461,338 -> 461,695
+808,777 -> 808,962
+902,459 -> 902,744
+793,703 -> 158,68
+100,919 -> 69,919
+912,785 -> 331,204
+712,609 -> 712,512
+268,762 -> 268,355
+972,667 -> 974,667
+647,647 -> 164,647
+589,180 -> 589,644
+836,258 -> 376,718
+676,977 -> 211,977
+626,608 -> 874,360
+271,911 -> 324,858
+182,374 -> 182,347
+14,989 -> 985,18
+461,462 -> 956,957
+82,79 -> 974,971
+607,478 -> 607,147
+898,76 -> 582,392
+326,31 -> 683,31
+768,47 -> 768,348
+35,386 -> 185,386
+803,391 -> 803,932
+879,486 -> 879,658
+183,39 -> 183,855
+431,467 -> 499,399
+434,306 -> 304,436
+774,618 -> 521,618
+364,426 -> 364,457
+44,849 -> 791,102
+70,850 -> 276,850
+181,838 -> 181,736
+574,18 -> 574,784
+103,613 -> 537,179
+34,218 -> 115,299
+808,777 -> 636,777
+483,112 -> 483,939
+15,790 -> 15,253
+433,427 -> 742,427
+829,947 -> 895,947
+361,180 -> 860,180
+124,499 -> 124,615
+879,712 -> 745,712
+16,12 -> 16,149
+36,981 -> 36,561
+929,52 -> 30,951
+845,85 -> 318,612
+114,731 -> 794,51
+434,280 -> 406,308
+530,513 -> 114,513
+417,715 -> 417,273
+44,845 -> 44,225
+951,122 -> 450,623
+32,707 -> 32,832
+51,58 -> 51,806
+165,305 -> 49,189
+517,221 -> 942,221
+125,233 -> 193,233
+903,180 -> 101,982
+123,303 -> 247,179
+199,174 -> 546,521
+185,860 -> 538,860
+825,751 -> 825,784
+454,720 -> 64,720
+28,10 -> 974,956
+626,760 -> 586,760
+91,234 -> 10,234
+973,939 -> 65,31
+589,308 -> 255,308
+547,945 -> 239,945
+909,914 -> 111,116
+484,182 -> 253,182
+145,575 -> 339,575
+215,143 -> 611,143
+963,983 -> 20,40
+220,733 -> 333,846
+126,860 -> 940,46
+715,823 -> 715,284
+832,65 -> 436,65
+923,496 -> 530,889
+708,517 -> 708,764
+154,681 -> 22,549
+909,135 -> 57,987
+225,966 -> 225,941
+629,491 -> 629,17
+927,349 -> 72,349
+15,987 -> 983,19
+265,912 -> 74,912
+14,985 -> 988,11
+986,64 -> 129,921
+697,831 -> 943,831
+379,143 -> 853,617
+232,887 -> 623,887
+947,473 -> 947,453
+898,762 -> 218,762
+599,386 -> 870,386
+757,137 -> 757,496
+437,285 -> 437,326
+515,311 -> 515,63
+305,703 -> 720,703
+321,770 -> 88,537
+75,48 -> 457,430
+38,499 -> 38,544
+481,896 -> 481,944
+614,483 -> 437,483
+647,430 -> 368,430
+641,669 -> 641,691
+849,626 -> 427,204
+805,688 -> 805,536
+102,315 -> 102,108
+729,525 -> 770,525
+234,702 -> 38,702
+17,457 -> 526,457
+369,155 -> 369,647
+216,118 -> 216,43
+342,384 -> 342,905
+470,832 -> 314,676
+179,318 -> 179,315
+40,707 -> 547,707
+771,236 -> 453,236
+113,823 -> 826,110
+731,642 -> 707,642
+36,398 -> 810,398
+233,447 -> 979,447
+74,286 -> 907,286
+939,223 -> 939,10
+866,57 -> 866,656
+978,20 -> 10,988
+816,176 -> 50,942
+293,868 -> 293,350
+900,159 -> 148,911
+58,84 -> 644,84
+720,416 -> 720,906
+935,31 -> 13,953
+41,727 -> 221,727
+633,112 -> 633,695
+418,947 -> 418,574
+632,711 -> 791,711
+73,228 -> 73,861
+59,447 -> 83,447
+418,938 -> 418,638
+922,352 -> 636,352
+66,773 -> 66,868
+69,678 -> 600,147
+333,251 -> 298,251
+371,803 -> 740,434
+976,972 -> 976,165
+896,415 -> 240,415
+672,476 -> 860,476
+202,291 -> 195,291
+99,971 -> 518,552
+284,858 -> 910,232
+187,282 -> 187,627
+157,445 -> 157,665
+421,879 -> 38,496
+155,431 -> 405,431
+772,472 -> 315,929
+69,818 -> 132,818
+70,328 -> 70,800
+471,788 -> 646,788
+960,900 -> 97,37
+258,566 -> 186,494
+345,413 -> 306,413
+897,173 -> 897,896
+74,740 -> 74,795
+679,238 -> 679,811
+870,64 -> 64,870
+30,869 -> 288,869
+539,380 -> 539,862
+452,692 -> 748,692
+527,712 -> 527,139
+725,504 -> 717,504
+201,338 -> 636,338
+626,719 -> 626,302
+580,153 -> 274,459
+654,215 -> 246,215
+363,738 -> 363,192
+335,502 -> 970,502
+266,52 -> 266,442
+125,127 -> 281,127

2021/06.rkt

@@ -0,0 +1,18 @@
+#lang br
+(require racket/file sugar rackunit)
+
+(define fish (map string->number (string-split (file->string "06.rktd") ",")))
+
+(define (simulate fish days)
+  (for/fold ([freqs (frequency-hash fish)]
+             #:result (apply + (hash-values freqs)))
+            ([d (in-range days)])
+    (hash-set*
+     (for/hasheq ([(k v) (in-hash freqs)]
+                  #:unless (zero? k))
+       (values (sub1 k) v))
+     6 (+ (hash-ref freqs 7 0) (hash-ref freqs 0 0))
+     8 (hash-ref freqs 0 0))))
+
+(check-equal? (simulate fish 80) 361169)
+(check-equal? (simulate fish 256) 1634946868992)

2021/06.rktd

@@ -0,0 +1 @@
+1,1,3,5,3,1,1,4,1,1,5,2,4,3,1,1,3,1,1,5,5,1,3,2,5,4,1,1,5,1,4,2,1,4,2,1,4,4,1,5,1,4,4,1,1,5,1,5,1,5,1,1,1,5,1,2,5,1,1,3,2,2,2,1,4,1,1,2,4,1,3,1,2,1,3,5,2,3,5,1,1,4,3,3,5,1,5,3,1,2,3,4,1,1,5,4,1,3,4,4,1,2,4,4,1,1,3,5,3,1,2,2,5,1,4,1,3,3,3,3,1,1,2,1,5,3,4,5,1,5,2,5,3,2,1,4,2,1,1,1,4,1,2,1,2,2,4,5,5,5,4,1,4,1,4,2,3,2,3,1,1,2,3,1,1,1,5,2,2,5,3,1,4,1,2,1,1,5,3,1,4,5,1,4,2,1,1,5,1,5,4,1,5,5,2,3,1,3,5,1,1,1,1,3,1,1,4,1,5,2,1,1,3,5,1,1,4,2,1,2,5,2,5,1,1,1,2,3,5,5,1,4,3,2,2,3,2,1,1,4,1,3,5,2,3,1,1,5,1,3,5,1,1,5,5,3,1,3,3,1,2,3,1,5,1,3,2,1,3,1,1,2,3,5,3,5,5,4,3,1,5,1,1,2,3,2,2,1,1,2,1,4,1,2,3,3,3,1,3,5

2021/07.rkt

@@ -0,0 +1,13 @@
+#lang br
+(require racket/file sugar rackunit)
+
+(define posns (map string->number (string-split (file->string "07.rktd") ",")))
+
+(define/caching (gauss-summation x) (* (/ x 2) (+ x 1)))
+
+(define (fuel-cost alignment [post-proc values])
+  (foldl (λ (posn res) (+ res (post-proc (abs (- alignment posn))))) 0 posns))
+
+(define possible-alignments (remove-duplicates posns))
+(check-equal? (apply min (map fuel-cost possible-alignments)) 349357)
+(check-equal? (apply min (map (λ (pa) (fuel-cost pa gauss-summation)) possible-alignments)) 96708205)

2021/07.rktd

@@ -0,0 +1 @@
+1101,1,29,67,1102,0,1,65,1008,65,35,66,1005,66,28,1,67,65,20,4,0,1001,65,1,65,1106,0,8,99,35,67,101,99,105,32,110,39,101,115,116,32,112,97,115,32,117,110,101,32,105,110,116,99,111,100,101,32,112,114,111,103,114,97,109,10,33,133,43,1060,890,12,15,136,42,25,96,694,522,893,204,204,1168,311,1046,1699,26,399,299,66,644,402,65,480,711,72,894,244,249,337,331,774,126,23,484,1299,662,404,235,86,1492,556,73,478,210,82,433,597,154,130,178,491,578,856,532,1191,544,256,831,252,1001,109,37,1290,317,376,22,742,496,930,118,28,376,73,247,942,895,38,675,138,387,203,271,104,65,1099,981,167,67,57,607,1095,202,225,1067,1757,324,127,785,266,518,135,914,1006,1402,578,28,548,211,673,302,525,208,115,92,514,518,71,1298,796,780,166,1341,475,273,101,1155,838,1219,901,727,497,168,543,416,174,31,755,865,106,358,236,186,369,550,465,617,375,535,1639,513,419,1377,1024,704,77,38,0,149,5,28,1163,149,1654,614,1201,89,1141,844,1390,1081,132,1385,52,1027,80,572,377,340,39,630,875,692,289,339,358,68,205,54,149,41,1208,1528,171,204,438,571,308,556,1372,426,204,18,31,51,40,287,1845,1721,441,240,875,901,328,800,341,59,530,134,275,11,7,7,1,1571,218,374,536,992,464,234,398,300,74,99,1163,1039,430,43,659,667,1115,407,257,717,657,249,46,109,734,67,1010,581,1070,738,478,621,183,224,1372,560,1573,1026,338,485,1138,1007,910,16,846,556,423,200,962,103,570,540,900,839,319,171,14,22,205,225,569,81,381,132,127,139,123,788,1571,35,830,65,677,1745,819,804,854,346,190,480,1500,76,1049,306,17,668,113,163,755,1015,718,1037,156,267,158,74,377,26,294,203,334,1186,88,384,853,404,290,135,620,668,234,1158,2,1102,137,884,287,15,638,1003,187,24,534,24,647,683,934,275,1844,887,1746,1614,1788,632,100,332,1565,1352,341,1027,475,958,289,1564,89,1138,233,535,790,990,863,889,45,44,169,251,522,11,41,104,45,828,1206,1515,645,39,544,382,1413,995,188,310,51,39,474,14,7,1387,809,428,77,8,867,1105,718,426,146,486,191,1251,677,1139,802,585,1140,46,39,128,867,49,33,198,731,349,661,296,103,22,444,1198,1149,188,245,492,1147,230,213,300,551,295,1313,365,975,587,1416,1213,233,257,631,564,876,434,1353,51,748,1179,1428,915,115,57,90,1312,892,200,1349,35,1010,445,619,1261,108,14,1424,481,381,209,154,23,972,646,593,6,289,171,543,97,28,401,290,298,14,37,1326,1177,533,67,75,294,328,527,449,455,176,345,226,729,210,55,45,0,834,887,123,1326,931,278,449,1278,608,217,411,143,447,16,1043,29,165,88,860,582,21,811,920,162,1788,15,423,1172,842,801,845,20,155,155,642,40,1036,560,348,689,328,505,84,1013,58,93,1653,233,233,383,380,84,617,1128,305,123,508,205,6,322,118,359,1186,84,677,640,80,1357,868,1035,8,64,995,1246,266,443,346,112,523,625,206,66,565,1878,25,1277,936,283,148,987,282,368,883,542,631,946,118,53,4,235,16,950,4,998,106,25,151,1013,27,1038,77,140,82,1119,236,125,947,1446,680,301,301,936,21,609,516,280,264,281,108,43,215,36,126,401,402,693,360,321,92,1809,305,551,86,77,278,81,524,400,1458,1342,897,49,35,518,288,655,91,398,38,251,647,79,400,151,520,459,960,425,663,298,584,90,533,690,610,755,56,19,21,244,548,1116,773,43,115,171,1127,103,1199,1470,176,451,693,65,186,262,963,137,1422,431,533,210,799,17,388,600,1113,2,181,815,1153,6,618,590,719,196,39,301,424,193,560,175,351,279,603,171,423,146,158,48,398,513,115,1,1051,817,200,473,143,261,435,856,1057,503,51,846,1020,177,1091,232,500,372,475,70,485,1227,1032,64,743,299,159,1077,18,204,944,1075,29,78,63,67,9,1007,354,1046,491,448,206,222,121,955,290,381,147,146,104,576,722,163,715,1475,130,1104,586,97,352,173,713,315,1482,1221,38,10,81,457,745,323,47,197,1012,1593,128,463,373,272,90,121,1248,1451,540,681,63,950,19,208,230,1362,1225,1500,207,81,739,288,626,261,1188,356,889,408,3,368,94,858,1512,834,43,5,833,826,33,791,800,39,299,1587,41,783,498,899,296,1189,470,66,307,892,47,207,199,902,17,14,1831,11,576,729,1436,153,142,81,165,214,1543,1464,561,737,180,162,515,867,65,74,200,9,11,539,19,305,996,334,297,1825,427,169,225,53,688,420,623,111,313,324,5,376,433,135,308,94

2021/08.rkt

@@ -0,0 +1,71 @@
+#lang br
+(require racket/file rackunit racket/dict)
+
+(define (parse-ints strs) (map (λ (str) (string-split str)) strs))
+
+(define recs
+  (let* ([lines (string-split (file->string "08.rktd") "\n")]
+         [sublines (map (λ (str) (string-split str "|")) lines)])
+    (map parse-ints sublines)))
+
+(define strlens (append-map (λ (vals) (map string-length vals)) (map second recs)))
+(check-equal? (count (λ (len) (memq len '(2 3 4 7))) strlens) 278)
+
+(require csp racket/set)
+
+(define (infer-config #:one one-digit #:four four-digit #:seven seven-digit #:five five-segment-digits)
+  (define prob (make-csp))
+  (add-vars! prob '(s1 s2 s3 s4 s5 s6 s7) '(a b c d e f g))
+  (add-all-diff-constraint! prob #:same eq?)
+  (add-constraint! prob  (λ (s3 s6) (equal? (set s3 s6) one-digit)) '(s3 s6))
+  (add-constraint! prob 
+                   (λ (s1 s2 s3 s4 s5 s6 s7)
+                     (define two-pattern (set s1 s3 s4 s5 s7))
+                     (define three-pattern (set s1 s3 s4 s6 s7))
+                     (define five-pattern (set s1 s2 s4 s6 s7))
+                     (for/and ([pat (list two-pattern three-pattern five-pattern)])
+                       (member pat five-segment-digits)))
+                   '(s1 s2 s3 s4 s5 s6 s7))
+  (add-constraint! prob (λ (s2 s3 s4 s6) (equal? (set s2 s3 s4 s6) four-digit)) '(s2 s3 s4 s6))
+  (add-constraint! prob (λ (s1 s3 s6) (equal? (set s1 s3 s6) seven-digit)) '(s1 s3 s6))
+  (solve prob))
+
+(define segments-table (list
+                        (cons (set 's1 's2 's3 's5 's6 's7) 0)
+                        (cons (set 's3 's6) 1)
+                        (cons (set 's1 's3 's4 's5 's7) 2)
+                        (cons (set 's1 's3 's4 's6 's7) 3)
+                        (cons (set 's2 's3 's4 's6) 4)
+                        (cons (set 's1 's2 's4 's6 's7) 5)
+                        (cons (set 's1 's2 's4 's5 's6 's7) 6)
+                        (cons (set 's1 's3 's6) 7)
+                        (cons (set 's1 's2 's3 's4 's5 's6 's7) 8)
+                        (cons (set 's1 's2 's3 's4 's6 's7) 9)))
+
+(define (string->symbols str) (map (λ (c) (string->symbol (string c))) (string->list str)))
+
+(define (wire-config strs)
+  (define encdoded-digits (map (compose1 list->set string->symbols) strs))
+  (define (filter-length len) (filter (λ (x) (= len (set-count x))) encdoded-digits))
+  (define one-digit (car (filter-length 2)))
+  (define four-digit (car (filter-length 4)))
+  (define seven-digit (car (filter-length 3)))
+  (define five-segment-digits (filter-length 5))
+  (infer-config #:one one-digit #:four four-digit #:seven seven-digit #:five five-segment-digits))
+
+(define (decode-number config pattern)
+  (define config-reverse (for/hasheq ([(k v) (in-dict config)])
+                           (values v k)))
+  (define segments (for/set ([item pattern])
+                     (d