Initial commit

2020/day01/day01.c

@@ -0,0 +1,49 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char *argv[]) {
+  if (argc < 2) {
+    printf("Usage: %s <input file>\n", argv[0]);
+    return 0;
+  }
+
+  FILE *fp = fopen(argv[1], "r");
+  if (fp == NULL) {
+    printf("Could not open file %s\n", argv[1]);
+    return 1;
+  }
+
+  int input[1024] = {0};
+  int d;
+  int n = 0;
+  while (fscanf(fp, "%d\n", &d) == 1) {
+    input[n] = d;
+    n++;
+  }
+  fclose(fp);
+
+  int res = -1;
+  for (int i = 0; i < n && res == -1; ++i) {
+    for (int j = 0; j < n && res == -1; ++j) {
+      if (input[i] + input[j] == 2020) {
+        res = input[i] * input[j];
+        break;
+      }
+    }
+  }
+  printf("%d\n", res);
+
+  res = -1;
+  for (int i = 0; i < n && res == -1; ++i) {
+    for (int j = 0; j < n && res == -1; ++j) {
+      for (int k = 0; k < n && res == -1; ++k) {
+        if (input[i] + input[j] + input[k] == 2020) {
+          res = input[i] * input[j] * input[k];
+        }
+      }
+    }
+  }
+  printf("%d\n", res);
+
+  return 0;
+}

2020/day01/day01.dyalog

@@ -0,0 +1,6 @@
+ ⎕io←0
+ x←⍎¨⊃⎕nget'input'1
+ ⍝ Part 1
+ ×/x[⊃⍸2020=x∘.+x]
+ ⍝ Part 2
+ ×/x[⊃⍸2020=⊃∘.+/3⍴⊂x]

2020/day01/day01.rkt

@@ -0,0 +1,37 @@
+#lang racket
+
+(module+ test
+  (require rackunit))
+
+(module+ main
+  (displayln "Day 1"))
+
+(define (read-input filename)
+  (map string->number (file->lines filename)))
+
+(define (part1 filename)
+  (define expenses (read-input filename))
+  (for*/last ([a (in-list expenses)]
+              [b (in-list expenses)]
+              #:final (= 2020 (+ a b)))
+    (* a b)))
+
+(module+ test
+  (check-eq? (part1 "test") 514579))
+
+(module+ main
+  (displayln (part1 "input")))
+
+(define (part2 filename)
+  (define expenses (read-input filename))
+  (for*/last ([a (in-list expenses)]
+              [b (in-list expenses)]
+              [c (in-list expenses)]
+              #:final (= 2020 (+ a b c)))
+    (* a b c)))
+
+(module+ test
+  (check-eq? (part2 "test") 241861950))
+
+(module+ main
+  (displayln (part2 "input")))

2020/day01/input

@@ -0,0 +1,200 @@
+1688
+1463
+1461
+1842
+1441
+1838
+1583
+1891
+1876
+1551
+1506
+2005
+1989
+1417
+1784
+1975
+1428
+1485
+1597
+1871
+105
+788
+1971
+1892
+1854
+1466
+1584
+1565
+1400
+1640
+1780
+1774
+360
+1421
+1368
+1771
+1666
+1707
+1627
+1449
+1677
+1504
+1721
+1994
+1959
+1862
+1768
+1986
+1904
+1382
+1969
+1852
+1917
+1966
+1742
+1371
+1405
+1995
+1906
+1694
+1735
+1422
+1719
+1978
+1641
+1761
+1567
+1974
+1495
+1973
+1958
+1599
+1770
+1600
+1465
+1865
+1479
+1687
+1390
+1802
+2008
+645
+1435
+1589
+1949
+1909
+1526
+1667
+1831
+1864
+1713
+1718
+1232
+1868
+1884
+1825
+1999
+1590
+1759
+1391
+1757
+323
+1612
+1637
+1727
+1783
+1643
+1442
+1452
+675
+1812
+1604
+1518
+1894
+1933
+1801
+1914
+912
+1576
+1961
+1970
+1446
+1985
+1988
+1563
+1826
+1409
+1503
+1539
+1832
+1698
+1990
+1689
+1532
+765
+1546
+1384
+1519
+1615
+1556
+1754
+1983
+1394
+1763
+1823
+1788
+1407
+1946
+1751
+1837
+1680
+1929
+1814
+1948
+1919
+1953
+55
+1731
+1516
+1895
+1795
+1890
+1881
+1799
+1536
+1396
+1942
+1798
+1767
+1745
+1883
+2004
+1550
+1916
+1650
+1749
+1991
+1789
+1740
+1490
+1873
+1003
+1699
+1669
+1781
+2000
+1728
+1877
+1733
+1588
+1168
+1828
+1848
+1963
+1928
+1920
+1493
+1968
+1564
+1572

2020/day01/test

@@ -0,0 +1,6 @@
+1721
+979
+366
+299
+675
+1456