2023 day 18, lucianoq

2023/18/Makefile

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+main1:
+	go build -o main1 main1.go common.go
+
+main2:
+	go build -o main2 main2.go common.go
+
+.PHONY: run1 run2 clean
+
+run1: main1
+	./main1 <input
+
+run2: main2
+	./main2 <input
+
+clean:
+	rm -f main1 main2
+

2023/18/assignment

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+--- Day 18: Lavaduct Lagoon ---
+
+   Thanks to your efforts, the machine parts factory is one of the first
+   factories up and running since the lavafall came back. However, to
+   catch up with the large backlog of parts requests, the factory will
+   also need a large supply of lava for a while; the Elves have already
+   started creating a large lagoon nearby for this purpose.
+
+   However, they aren't sure the lagoon will be big enough; they've asked
+   you to take a look at the dig plan (your puzzle input). For example:
+
+        R 6 (#70c710)
+        D 5 (#0dc571)
+        L 2 (#5713f0)
+        D 2 (#d2c081)
+        R 2 (#59c680)
+        D 2 (#411b91)
+        L 5 (#8ceee2)
+        U 2 (#caa173)
+        L 1 (#1b58a2)
+        U 2 (#caa171)
+        R 2 (#7807d2)
+        U 3 (#a77fa3)
+        L 2 (#015232)
+        U 2 (#7a21e3)
+
+   The digger starts in a 1 meter cube hole in the ground. They then dig
+   the specified number of meters up ( U ), down ( D ), left ( L ), or
+   right ( R ), clearing full 1 meter cubes as they go. The directions are
+   given as seen from above, so if "up" were north, then "right" would be
+   east, and so on. Each trench is also listed with the color that the
+   edge of the trench should be painted as an [1]RGB hexadecimal color
+   code .
+
+   When viewed from above, the above example dig plan would result in the
+   following loop of trench ( # ) having been dug out from otherwise
+   ground-level terrain ( . ):
+
+        #######
+        #.....#
+        ###...#
+        ..#...#
+        ..#...#
+        ###.###
+        #...#..
+        ##..###
+        .#....#
+        .######
+
+   At this point, the trench could contain 38 cubic meters of lava.
+   However, this is just the edge of the lagoon; the next step is to dig
+   out the interior so that it is one meter deep as well:
+
+        #######
+        #######
+        #######
+        ..#####
+        ..#####
+        #######
+        #####..
+        #######
+        .######
+        .######
+
+   Now, the lagoon can contain a much more respectable 62 cubic meters of
+   lava. While the interior is dug out, the edges are also painted
+   according to the color codes in the dig plan.
+
+   The Elves are concerned the lagoon won't be large enough; if they
+   follow their dig plan, how many cubic meters of lava could it hold?
+
+--- Part Two ---
+
+   The Elves were right to be concerned; the planned lagoon would be much
+   too small .
+
+   After a few minutes, someone realizes what happened; someone swapped
+   the color and instruction parameters when producing the dig plan. They
+   don't have time to fix the bug; one of them asks if you can extract the
+   correct instructions from the hexadecimal codes.
+
+   Each hexadecimal code is six hexadecimal digits long. The first five
+   hexadecimal digits encode the distance in meters as a five-digit
+   hexadecimal number. The last hexadecimal digit encodes the direction to
+   dig : 0 means R , 1 means D , 2 means L , and 3 means U .
+
+   So, in the above example, the hexadecimal codes can be converted into
+   the true instructions:
+     * #70c710 = R 461937
+     * #0dc571 = D 56407
+     * #5713f0 = R 356671
+     * #d2c081 = D 863240
+     * #59c680 = R 367720
+     * #411b91 = D 266681
+     * #8ceee2 = L 577262
+     * #caa173 = U 829975
+     * #1b58a2 = L 112010
+     * #caa171 = D 829975
+     * #7807d2 = L 491645
+     * #a77fa3 = U 686074
+     * #015232 = L 5411
+     * #7a21e3 = U 500254
+
+   Digging out this loop and its interior produces a lagoon that can hold
+   an impressive 952408144115 cubic meters of lava.
+
+   Convert the hexadecimal color codes into the correct instructions; if
+   the Elves follow this new dig plan, how many cubic meters of lava could
+   the lagoon hold?
+
+References
+
+   1. https://en.wikipedia.org/wiki/RGB_color_model#Numeric_representations

2023/18/common.go

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+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+)
+
+type Op struct {
+	Dir   string
+	Steps int
+	Color string
+}
+
+type P struct{ R, C int }
+
+var Delta = map[string]P{
+	"U": {-1, 0},
+	"R": {0, 1},
+	"D": {1, 0},
+	"L": {0, -1},
+}
+
+func parse() []Op {
+	scanner := bufio.NewScanner(os.Stdin)
+	var ops []Op
+	for scanner.Scan() {
+		line := scanner.Text()
+
+		var op Op
+		_, _ = fmt.Sscanf(line, "%s %d %s", &op.Dir, &op.Steps, &op.Color)
+		op.Color = strings.Trim(op.Color, "()#")
+		ops = append(ops, op)
+	}
+	return ops
+}