Day 25 Merry Christmas!

day25p1/solution.go

@@ -0,0 +1,79 @@
+package day25p1
+
+import (
+	"io"
+
+	"aoc/utils"
+)
+
+type Key [5]int
+type Lock [5]int
+
+func (k Key) toLock() Lock {
+	var lock Lock
+	for i, v := range k {
+		lock[i] = v
+	}
+	return lock
+}
+
+func Solve(r io.Reader) any {
+	blocks := utils.ReadBlocks(r)
+
+	keys := make([]Key, 0)
+	locks := make([]Lock, 0)
+
+	for _, block := range blocks {
+		isKey := checkKey(block)
+		if isKey {
+			keys = append(keys, parseKey(block))
+		} else {
+			locks = append(locks, parseLock(block))
+		}
+	}
+
+	nonoverlapping := 0
+
+	for _, key := range keys {
+		for _, lock := range locks {
+			overlapping := false
+			for i := 0; i < 5; i++ {
+				if key[i]+lock[i] > 5 {
+					overlapping = true
+					break
+				}
+			}
+			if !overlapping {
+				nonoverlapping += 1
+			}
+		}
+	}
+
+	return nonoverlapping
+}
+
+func checkKey(block []string) bool {
+	if block[0] == "....." {
+		return true
+	} else if block[0] == "#####" {
+		return false
+	} else {
+		panic("Invalid block")
+	}
+}
+
+func parseKey(block []string) Key {
+	var key Key
+	for _, row := range block[1 : len(block)-1] {
+		for j, c := range row {
+			if c == '#' {
+				key[j] += 1
+			}
+		}
+	}
+	return key
+}
+
+func parseLock(block []string) Lock {
+	return parseKey(block).toLock()
+}

day25p1/solution_test.go

@@ -0,0 +1,71 @@
+package day25p1
+
+import (
+	"strings"
+	"testing"
+
+	"aoc/utils"
+)
+
+var testInput = `#####
+.####
+.####
+.####
+.#.#.
+.#...
+.....
+
+#####
+##.##
+.#.##
+...##
+...#.
+...#.
+.....
+
+.....
+#....
+#....
+#...#
+#.#.#
+#.###
+#####
+
+.....
+.....
+#.#..
+###..
+###.#
+###.#
+#####
+
+.....
+.....
+.....
+#....
+#.#..
+#.#.#
+#####`
+
+func TestSolve(t *testing.T) {
+	tests := []struct {
+		input  string
+		answer int
+	}{
+		{testInput, 3},
+	}
+
+	if testing.Verbose() {
+		utils.Verbose = true
+	}
+
+	for _, test := range tests {
+		r := strings.NewReader(test.input)
+
+		result := Solve(r).(int)
+
+		if result != test.answer {
+			t.Errorf("Expected %d, got %d", test.answer, result)
+		}
+	}
+}

utils/functions.go

@@ -61,6 +61,31 @@ func ReadLines(r io.Reader) []string {
 	return result
 }
 
+// Read until \n\n and return blocks of lines
+func ReadBlocks(r io.Reader) [][]string {
+	result := [][]string{}
+
+	scanner := bufio.NewScanner(r)
+	block := []string{}
+	for scanner.Scan() {
+		line := scanner.Text()
+		if line == "" {
+			result = append(result, block)
+			block = []string{}
+		} else {
+			block = append(block, line)
+		}
+	}
+	err := scanner.Err()
+	Check(err, "error reading blocks")
+
+	if len(block) > 0 {
+		result = append(result, block)
+	}
+
+	return result
+}
+
 func GetInts(s string) []int {
 	matches := intRegex.FindAllString(s, -1)
 	result := make([]int, len(matches))