init day 7

2021/day07/EXAMPLE.txt

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+16,1,2,0,4,2,7,1,2,14

2021/day07/INPUT.txt

@@ -0,0 +1 @@
+1101,1,29,67,1102,0,1,65,1008,65,35,66,1005,66,28,1,67,65,20,4,0,1001,65,1,65,1106,0,8,99,35,67,101,99,105,32,110,39,101,115,116,32,112,97,115,32,117,110,101,32,105,110,116,99,111,100,101,32,112,114,111,103,114,97,109,10,322,659,689,304,1706,69,576,110,238,904,299,206,78,954,776,590,404,125,235,438,472,187,205,620,14,378,1056,496,1323,59,44,636,432,658,30,195,107,425,105,214,908,145,641,1467,441,346,455,1454,773,146,97,42,509,8,1217,503,901,1147,1654,45,1438,503,62,851,590,105,217,44,646,197,491,333,1224,90,262,1132,1499,864,128,165,36,646,422,1265,501,414,328,170,1566,115,1049,154,224,490,1018,1019,1484,315,614,816,207,240,423,132,196,484,532,857,341,723,69,294,787,1020,691,185,525,697,1435,62,156,21,314,489,640,93,415,446,902,15,510,91,104,317,971,108,187,616,794,416,1332,499,1086,443,514,258,383,162,1034,1,331,269,283,1835,150,1698,1020,318,1540,687,17,889,585,1682,67,547,1,1353,149,1650,145,13,151,1144,409,294,740,676,267,827,1624,804,44,795,297,265,426,508,11,1359,963,277,203,1093,450,1229,287,160,1913,914,512,1098,103,975,64,26,787,87,104,340,362,153,173,93,455,89,577,40,1459,320,398,1245,12,452,515,594,0,1497,1238,88,14,538,431,0,699,1033,483,574,593,612,770,1006,332,23,753,1334,536,109,164,250,86,333,1577,896,1199,521,73,467,1037,0,539,375,1243,238,301,262,191,415,88,515,1410,54,1019,934,81,1273,78,306,57,145,472,57,682,203,63,512,427,104,457,214,197,1766,350,355,536,839,7,586,1209,71,88,858,562,64,335,84,1161,1305,1203,102,52,193,47,852,718,885,146,111,1014,667,8,52,637,254,1453,674,1542,47,107,55,321,591,829,1113,40,215,398,254,327,181,200,20,129,265,109,705,1265,12,148,367,349,333,341,272,90,166,699,681,1927,1267,86,282,299,36,48,1594,110,645,569,724,199,334,239,117,448,108,67,1257,142,902,208,728,700,107,1,621,1036,1397,837,313,380,208,156,39,220,238,648,197,26,2,1010,98,458,271,1237,99,751,31,236,26,622,802,4,121,244,240,67,462,1181,100,1381,1494,446,23,35,95,357,212,90,820,56,96,171,11,1101,1020,149,125,1504,896,25,8,1704,193,421,134,135,1397,1052,1059,741,967,1537,373,585,279,46,398,654,305,435,89,11,702,27,102,573,497,139,530,805,3,122,1329,175,134,137,57,516,790,587,163,296,153,1124,1336,946,63,39,278,13,253,237,653,200,250,1067,1891,697,182,628,0,60,303,389,1821,189,295,41,619,71,795,1228,110,1198,306,941,59,72,666,610,850,984,564,330,636,111,1541,542,80,212,927,127,427,33,365,313,697,200,286,708,478,264,448,1159,256,28,273,7,238,176,956,735,264,361,1882,139,1345,1,271,508,0,190,110,119,76,715,1338,80,1026,132,286,966,337,1715,514,328,265,63,1376,1413,1421,457,66,1594,737,59,548,184,801,165,96,129,1200,50,604,1013,309,627,625,597,1012,77,670,177,264,115,174,109,148,270,24,346,33,1270,359,954,113,207,484,1756,1155,1067,991,1358,61,530,612,135,351,706,244,489,609,484,76,168,258,161,694,1019,1502,558,117,112,1041,1040,448,879,37,616,930,32,357,1650,231,458,1068,585,9,439,412,292,116,494,246,28,260,463,200,84,1106,750,667,1284,129,878,1077,453,960,409,1327,412,243,89,616,443,256,645,1083,526,95,818,9,59,76,541,312,1168,430,64,2,187,561,1322,369,1245,64,854,126,359,240,42,157,35,232,863,74,331,250,695,914,182,208,94,656,87,530,1444,163,429,46,299,1038,38,471,91,112,819,1644,244,1718,76,806,103,752,124,796,1183,15,829,1038,6,529,913,140,326,435,44,617,659,123,753,444,467,408,182,1387,202,684,60,55,26,155,902,1075,86,375,924,862,150,1230,700,143,417,156,933,872,639,1032,137,146,1649,1562,4,11,257,556,29,1440,177,935,741,492,300,1530,92,453,56,244,37,997,762,624,456,1182,845,150,367,393,334,338,100,278,1374,267,1261,25,106,332,25,2,14,123,288,600,880,838,323,183,1075,202,445,218,1538,73,300,555,322,587,7,606,753,676,28,57,557,1283,23,73,31,370,29,491,5,31,97,199,188,1088,276,1061,1043,42,1463,601,56,255,426,150,1451,562,0,408,7,701,111,1145,838,976,310,561,645,33,213,1020,73,81,849,2,586,825,183,2,704,59,1515,906,647,91,585,14,778,333,258,353,128,839,146,81,231,128,716,699,64,345,812,906,1180,286,243,295,1031,197,1392

2021/day07/Makefile

@@ -0,0 +1,55 @@
+# AOC daily Makefile - GNU make only.
+#
+# Copyright (C) 2021 Bruno Raoult ("br")
+# Licensed under the GNU General Public License v3.0 or later.
+# Some rights reserved. See COPYING.
+#
+# You should have received a copy of the GNU General Public License along with this
+# program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.html>.
+#
+# SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
+#
+
+INPUT   := INPUT.txt
+SHELL   := /bin/bash
+
+CC      := gcc
+
+LIB     := aoc_$(shell uname -m)
+INCDIR  := ../include
+LIBDIR  := ../lib
+LDFLAGS := -L$(LIBDIR)
+LDLIB   := -l$(LIB)
+
+export LD_LIBRARY_PATH = $(LIBDIR)
+
+CFLAGS += -std=gnu99
+CFLAGS += -O2
+CFLAGS += -g
+CFLAGS += -Wall
+CFLAGS += -Wextra
+CFLAGS += -march=native
+CFLAGS += -Wmissing-declarations
+CFLAGS += -Wno-unused-result
+
+TIME   := \time -f "\ttime: %E real, %U user, %S sys\n\tcontext-switch:\t%c+%w, page-faults: %F+%R\n"
+export PATH := .:$(PATH)
+
+.PHONY: clean all compile ex1 ex2
+
+all: ex1 ex2
+
+compile: aoc-c
+
+ex1: aoc-c
+	@$(TIME) aoc-c -p 1 < $(INPUT)
+
+ex2: aoc-c
+	@$(TIME) aoc-c -p 2 < $(INPUT)
+
+clean:
+	@rm -f aoc-c core*
+
+.c:
+	@echo compiling $<
+	@$(CC) $(CFLAGS) $(LDFLAGS) -I $(INCDIR) $< $(LDLIB) -o $@

2021/day07/README.txt

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+--- Day 7: The Treachery of Whales ---
+
+A giant whale has decided your submarine is its next meal, and it's much faster than you are. There's nowhere to run!
+
+Suddenly, a swarm of crabs (each in its own tiny submarine - it's too deep for them otherwise) zooms in to rescue you! They seem to be preparing to blast a hole in the ocean floor; sensors indicate a massive underground cave system just beyond where they're aiming!
+
+The crab submarines all need to be aligned before they'll have enough power to blast a large enough hole for your submarine to get through. However, it doesn't look like they'll be aligned before the whale catches you! Maybe you can help?
+
+There's one major catch - crab submarines can only move horizontally.
+
+You quickly make a list of the horizontal position of each crab (your puzzle input). Crab submarines have limited fuel, so you need to find a way to make all of their horizontal positions match while requiring them to spend as little fuel as possible.
+
+For example, consider the following horizontal positions:
+
+16,1,2,0,4,2,7,1,2,14
+
+This means there's a crab with horizontal position 16, a crab with horizontal position 1, and so on.
+
+Each change of 1 step in horizontal position of a single crab costs 1 fuel. You could choose any horizontal position to align them all on, but the one that costs the least fuel is horizontal position 2:
+
+    Move from 16 to 2: 14 fuel
+    Move from 1 to 2: 1 fuel
+    Move from 2 to 2: 0 fuel
+    Move from 0 to 2: 2 fuel
+    Move from 4 to 2: 2 fuel
+    Move from 2 to 2: 0 fuel
+    Move from 7 to 2: 5 fuel
+    Move from 1 to 2: 1 fuel
+    Move from 2 to 2: 0 fuel
+    Move from 14 to 2: 12 fuel
+
+This costs a total of 37 fuel. This is the cheapest possible outcome; more expensive outcomes include aligning at position 1 (41 fuel), position 3 (39 fuel), or position 10 (71 fuel).
+
+Determine the horizontal position that the crabs can align to using the least fuel possible. How much fuel must they spend to align to that position?