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diff --git a/posts/2020-12-04-aoc-2020-day-1-in-cbm-basic.html b/posts/2020-12-04-aoc-2020-day-1-in-cbm-basic.html deleted file mode 100644 index 66aabd2..0000000 --- a/posts/2020-12-04-aoc-2020-day-1-in-cbm-basic.html +++ /dev/null @@ -1,231 +0,0 @@ -<!DOCTYPE html> -<html lang="en"> - <head> - <link rel="stylesheet" href="/includes/stylesheet.css" /> - <meta charset="utf-8" /> - <meta name="viewport" content="width=device-width, initial-scale=1" /> - <meta - property="og:description" - content="The World Wide Web pages of Adam Carpenter" - /> - <meta property="og:image" content="https://nextcloud.53hor.net/index.php/s/Nx9e7iHbw4t99wo/preview" /> - <meta property="og:site_name" content="53hor.net" /> - <meta property="og:title" content="AOC 2020 Day 1 in CBM Basic" /> - <meta property="og:type" content="website" /> - <meta property="og:url" content="https://www.53hor.net" /> - <title>53hornet ➙ AOC 2020 Day 1 in CBM Basic</title> - </head> - - <body> - <nav> - <ul> - <li> - <a href="/"> - <img alt="home" src="/includes/icons/home-roof.svg" /> - Home - </a> - </li> - <li> - <a href="/info.html"> - <img alt="information" src="/includes/icons/information-variant.svg" /> - Info - </a> - </li> - <li> - <a href="https://git.53hor.net"> - <img alt="git" src="/includes/icons/git.svg" /> - Repos - </a> - </li> - <li> - <a href="/software.html"> - <img alt="software" src="/includes/icons/floppy-variant.svg" /> - Software - </a> - </li> - <li> - <a type="application/rss+xml" href="/rss.xml"> - <img alt="rss" src="/includes/icons/rss.svg" /> - RSS - </a> - </li> - </ul> - </nav> - - <article> - <h1>AOC 2020 Day 1 in CBM Basic</h1> - - <p class="description"> - I implemented the - <a href="https://adventofcode.com/2020">Advent of Code 2020</a> Day 1 - challenge in CBM BASIC on a real Commodore 64. I haven't done anything - in Basic in a long time, and probably never did anything actually - meaningful with it. Part 1 of the challenge was to take a list of - numbers, find the two that summed to 2020, and then multiply those two - numbers together. Part two was to perform part 1 but with three numbers - instead of two. - </p> - <p> - Now I wanted to actually write the code on the Commodore 64 itself, but - I gave myself some leniency. Instead of manually typing in all 200 - entries of input data (and inevitably making a breaking mistake) I used - Vim on my PC to format the <code>DATA</code> entries at the start of the - code. I then dropped that onto a 1541 disk image, plopped it on an SD - card, and used my SD2IEC to mount the SD card's image on the Commodore. - The rest of the programming was done on the Commodore itself. - </p> - - <p>Here is my solution for Day 1 Part 1:</p> - <pre> - <code> -10 DATA 1686, 1983, 1801, 1890, 1910, 1722, 1571, 1952, 1602, 1551, 1144 -11 DATA 1208, 1335, 1914, 1656, 1515, 1600, 1520, 1683, 1679, 1800, 1889 -12 DATA 1717, 1592, 1617, 1756, 1646, 1596, 1874, 1595, 1660, 1748, 1946 -13 DATA 1734, 1852, 2006, 1685, 1668, 1607, 1677, 403 , 1312, 1828, 1627 -14 DATA 1925, 1657, 1536, 1522, 1557, 1636, 1586, 1654, 1541, 1363, 1844 -15 DATA 1951, 1765, 1872, 696, 1764, 1718, 1540, 1493, 1947, 1786, 1548 -16 DATA 1981, 1861, 1589, 1707, 1915, 1755, 1906, 1911, 1628, 1980, 1986 -17 DATA 1780, 1645, 741 , 1727, 524 , 1690, 1732, 1956, 1523, 1534, 1498 -18 DATA 1510, 372 , 1777, 1585, 1614, 1712, 1650, 702 , 1773, 1713, 1797 -19 DATA 1691, 1758, 1973, 1560, 1615, 1933, 1281, 1899, 1845, 1752, 1542 -20 DATA 1694, 1950, 1879, 1684, 1809, 1988, 1978, 1843, 1730, 1377, 1507 -21 DATA 1506, 1566, 935 , 1851, 1995, 1796, 1900, 896 , 171, 1728, 1635 -22 DATA 1810, 2003, 1580, 1789, 1709, 2007, 1639, 1726, 1537, 1976, 1538 -23 DATA 1544, 1626, 1876, 1840, 1953, 1710, 1661, 1563, 1836, 1358, 1550 -24 DATA 1112, 1832, 1555, 1394, 1912, 1884, 1524, 1689, 1775, 1724, 1366 -25 DATA 1966, 1549, 1931, 1975, 1500, 1667, 1674, 1771, 1631, 1662, 1902 -26 DATA 1970, 1864, 2004, 2010, 504 , 1714, 1917, 1907, 1704, 1501, 1812 -27 DATA 1349, 1577, 1638, 1886, 1157, 1761, 1676, 1731, 2001, 1261, 1154 -28 DATA 1769, 1529 -100 DIM A(200) -110 FOR I=0TO199 -120 READ A(I) -140 NEXT -150 FOR I=0TO199 -160 B=A(I) -170 FOR J=0TO199 -180 IF I=J THEN 210 -190 C=A(J) -200 IF B+C=2020 THEN PRINT "!",B,C,B*C:STOP -210 NEXT J -220 NEXT I - </code></pre> - - <p> - I basically put all 200 numbers into data fields, and then defined an - array large enough to read them into with <code>DIM</code>. Then I - iterated over the array twice, checking each element against each other - element to see if they summed to 2020. If they did, I printed them both - and the product of the two found numbers and stopped further execution. - </p> - <p> - There weren't really any special tricks to this implementation except - remembering that I shouldn't be checking whether a number could sum to - 2020 with itself. - </p> - - <p> - Then I got to move onto Part 2, and this is where things got - interesting. Comparing any three numbers from the data meant the - cognitively easiest way to solve the problem was a triple loop. This of - course meant <code>O(n^3)</code> time, which the Commodore struggled - with. I waited about an hour before I decided I could optimize just a - little bit to speed up the search. - </p> - - <p> - I figured that for three numbers to sum to 2020, they all had to be - pretty small. Most likely they were most (if not all) three digits - instead of four. So I figured I could sort the entry data to make the - search finish probably near the start of the first layer of iteration. - Keep in mind I didn't want to pre-sort the data, I wanted the Commodore - to work with the same exact input set it had for Part 1. So I turned to - the simplest sorting algorithm I could remember: - <a href="https://en.wikipedia.org/wiki/Bubble_sort">bubble sort</a>. - </p> - - <p>Here is my solution for Day 1 Part 2:</p> - - <pre> - <code> -10 DATA 1686, 1983, 1801, 1890, 1910, 1722, 1571, 1952, 1602, 1551, 1144 -11 DATA 1208, 1335, 1914, 1656, 1515, 1600, 1520, 1683, 1679, 1800, 1889 -12 DATA 1717, 1592, 1617, 1756, 1646, 1596, 1874, 1595, 1660, 1748, 1946 -13 DATA 1734, 1852, 2006, 1685, 1668, 1607, 1677, 403 , 1312, 1828, 1627 -14 DATA 1925, 1657, 1536, 1522, 1557, 1636, 1586, 1654, 1541, 1363, 1844 -15 DATA 1951, 1765, 1872, 696, 1764, 1718, 1540, 1493, 1947, 1786, 1548 -16 DATA 1981, 1861, 1589, 1707, 1915, 1755, 1906, 1911, 1628, 1980, 1986 -17 DATA 1780, 1645, 741 , 1727, 524 , 1690, 1732, 1956, 1523, 1534, 1498 -18 DATA 1510, 372 , 1777, 1585, 1614, 1712, 1650, 702 , 1773, 1713, 1797 -19 DATA 1691, 1758, 1973, 1560, 1615, 1933, 1281, 1899, 1845, 1752, 1542 -20 DATA 1694, 1950, 1879, 1684, 1809, 1988, 1978, 1843, 1730, 1377, 1507 -21 DATA 1506, 1566, 935 , 1851, 1995, 1796, 1900, 896 , 171, 1728, 1635 -22 DATA 1810, 2003, 1580, 1789, 1709, 2007, 1639, 1726, 1537, 1976, 1538 -23 DATA 1544, 1626, 1876, 1840, 1953, 1710, 1661, 1563, 1836, 1358, 1550 -24 DATA 1112, 1832, 1555, 1394, 1912, 1884, 1524, 1689, 1775, 1724, 1366 -25 DATA 1966, 1549, 1931, 1975, 1500, 1667, 1674, 1771, 1631, 1662, 1902 -26 DATA 1970, 1864, 2004, 2010, 504 , 1714, 1917, 1907, 1704, 1501, 1812 -27 DATA 1349, 1577, 1638, 1886, 1157, 1761, 1676, 1731, 2001, 1261, 1154 -28 DATA 1769, 1529 -100 DIM A(200) -110 FOR I=0TO199 -120 READ A(I) -140 NEXT -141 GOSUB 300 -150 FOR I=0TO199 -160 B=A(I) -170 FOR J=0TO199 -180 IF J=I THEN 250 -190 C=A(J) -200 FOR K=0TO199 -210 IF K=I OR K=J THEN 240 -220 D=A(K) -230 IF B+C+D=2020 THEN PRINT "!",B,C,D,B*C*D:STOP -240 NEXT K -250 NEXT J -260 NEXT I -300 REM BUBBLE SORT -301 X=200 -310 N=200 -320 FOR I=0TON-2 -330 FOR J=0TON-I-2 -340 X=A(J):Y=A(J+1) -350 IF X>Y THEN A(J)=Y:A(J+1)=X -360 NEXT : NEXT -370 RETURN - </code> - </pre> - - <p> - I added a subroutine starting on line 300 to perform a basic bubble sort - on top of the original array of data. Now bubble sort isn't fast by any - means, but the Commodore was able to finish it in a couple of minutes. - And the results were worth it because the subsequent triple - <code>FOR</code>-loop completed in another few minutes. My instinct was - right and two of the solution numbers were triple-digit. - </p> - - <p> - So there you have it, Advent of Code 2020 Day 1 in Commodore 64 Basic - V2. You can run these samples on real hardware of course, or in an - emulator. You can also run them with the - <a href="https://github.com/mist64/cbmbasic"><code>cbmbasic</code></a> - interpreter, which is a neat native C64 Basic interpreter for modern - architectures. (Oh and I tested my samples on <code>cbmbasic</code> and - they finished instantaneously. It helps to have a - thousands-of-times-faster processor.) - </p> - - <p> - I was going to keep going with the challenge and finish them all in CBM - basic for fun, but the Day 2 input data set was 1000 entries. No - problem, I can just read them from a <code>SEQ</code> file. The only - blocker I realized was the challenge requires string character counting, - which I don't think there's a function for in CBM basic. Maybe I have to - do a few <code>PEEK</code>s and <code>POKE</code>s to check memory - locations for ASCII/PETSCII character codes. Or I could just put it off - til next year :) - </p> - </article> - </body> -</html> |