begin day 10

day10.go

@@ -0,0 +1,92 @@
+package main
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"log"
+	"unicode"
+)
+
+type groundpipe struct {
+	value byte // value of the pipe
+
+	// byte slices should be sorted to allow for easier comparison
+	north []byte // valid byte set for a pipe to the north
+	south []byte // valid byte set for a pipe to the south
+	east  []byte // valid byte set for a pipe to the east
+	west  []byte // valid byte set for a pipe to the west
+}
+
+type day10 struct{}
+
+func scanmaze(r io.Reader) ([][]groundpipe, int, int) {
+	layers := make([][]groundpipe, 0)
+	row, col := 0, 0
+	buf := bufio.NewReader(r)
+
+	for next := true; next; {
+		bts, err := buf.ReadBytes('\n')
+		next = !reachedeof(err)
+
+		layers = append(layers, make([]groundpipe, 0))
+		end := len(layers) - 1
+
+		for i, b := range bytes.TrimFunc(bts, unicode.IsSpace) {
+			pipe := groundpipe{value: b}
+			switch b {
+			case '|':
+				pipe.north = []byte("7F|")
+				pipe.south = []byte("JL|")
+				// pipe.east = []byte("")
+				// pipe.west = []byte("")
+			case '-':
+				// pipe.north = []byte("")
+				// pipe.south = []byte("")
+				pipe.east = []byte("-7J")
+				pipe.west = []byte("-FL")
+			case 'L':
+				pipe.north = []byte("7F|")
+				// pipe.south = []byte("")
+				pipe.east = []byte("-7J")
+				// pipe.west = []byte("")
+			case 'J':
+				pipe.north = []byte("7F|")
+				// pipe.south = []byte("")
+				// pipe.east = []byte("")
+				pipe.west = []byte("-FL")
+			case '7':
+				// pipe.north = []byte("")
+				pipe.south = []byte("JL|")
+				// pipe.east = []byte("")
+				pipe.west = []byte("-FL")
+			case 'F':
+				// pipe.north = []byte("")
+				pipe.south = []byte("JL|")
+				pipe.east = []byte("-7J")
+				// pipe.west = []byte("")
+			case 'S':
+				row, col = end, i
+			default:
+				// ignoring '.' and '\n'
+				continue
+			}
+			layers[end] = append(layers[end], pipe)
+		}
+	}
+
+	return layers, row, col
+}
+
+func (d day10) solve1(r io.Reader) string {
+	_, startx, starty := scanmaze(r)
+	log.Printf("x: %d; y: %d", startx, starty)
+	farthest := 0
+
+	return fmt.Sprintf("%d", farthest)
+}
+
+func (d day10) solve2(r io.Reader) string {
+	return "incomplete"
+}

main.go

@@ -29,6 +29,7 @@ var (
 		&day07{},
 		&day08{},
 		&day09{},
+		&day10{},
 	}
 )
 

main_test.go

@@ -163,10 +163,19 @@ ZZZ = (ZZZ, ZZZ)`,
 		{
 			// day 9
 			inp1: `0 3 6 9 12 15
-1 3 6 10 15 21
+                   1 3 6 10 15 21
-10 13 16 21 30 45`,
+                   10 13 16 21 30 45`,
 			ans1: "114",
 			ans2: "2",
 		},
+		{
+			// day 10
+			inp1: `..F7.
+			       .FJ|.
+			       SJ.L7
+			       |F--J
+			       LJ...`,
+			ans1: "8",
+		},
 	}
 )