Day 10

10/input.txt

@@ -0,0 +1,96 @@
+70
+102
+148
+9
+99
+63
+40
+52
+91
+39
+55
+28
+54
+22
+95
+61
+118
+35
+14
+21
+129
+82
+137
+45
+7
+87
+81
+25
+3
+108
+41
+11
+145
+18
+65
+80
+115
+29
+136
+42
+97
+104
+117
+141
+62
+121
+23
+96
+24
+128
+48
+1
+112
+8
+34
+144
+134
+116
+58
+147
+51
+84
+17
+126
+64
+68
+135
+10
+77
+105
+127
+73
+111
+90
+16
+103
+109
+98
+146
+123
+130
+69
+133
+110
+30
+122
+15
+74
+33
+38
+83
+92
+2
+53
+140
+4

10/main.go

@@ -0,0 +1,57 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"sort"
+	"strconv"
+)
+
+func main() {
+	// Part 1
+
+	joltages := []int{}
+
+	file, _ := os.Open("input.txt")
+	defer file.Close()
+	for scanner := bufio.NewScanner(file); scanner.Scan(); {
+		joltage, _ := strconv.Atoi(scanner.Text())
+		joltages = append(joltages, joltage)
+	}
+
+	sort.Ints(joltages)
+
+	jolts := map[int]int{}
+	currentJolt := 0
+
+	for _, j := range joltages {
+		jolts[j-currentJolt]++
+		currentJolt = j
+	}
+
+	// Device itself
+	jolts[3]++
+
+	fmt.Println("Part 1:", jolts[1]*jolts[3])
+
+	// Part 2
+
+	fmt.Println("Part 2:", countPaths(0, joltages, map[int]int{}))
+}
+
+func countPaths(current int, joltages []int, memory map[int]int) (total int) {
+	if len(joltages) == 0 {
+		return 1
+	}
+	for _, next := range joltages {
+		if next-current > 3 {
+			break
+		}
+		if _, exists := memory[next]; !exists {
+			memory[next] = countPaths(next, joltages[1:], memory)
+		}
+		total += memory[next]
+	}
+	return
+}