2020/day10.go

@@ -1,121 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"log"
-	"os"
-
-	"git.annabunch.es/annabunches/adventofcode/2020/lib/fileutils"
-)
-
-func getMax(values map[int]bool) int {
-	max := 0
-	for value, _ := range values {
-		if value > max {
-			max = value
-		}
-	}
-
-	return max
-}
-
-type Node struct {
-	Value    int
-	Children []*Node
-	Paths    int // the total number of paths from here to some target
-}
-
-// Build a tree of possible paths, then count them.
-func findArrangements(values map[int]bool, target int) int {
-	root := buildTree(values, target)
-	return countPaths(root, target)
-}
-
-func buildTree(values map[int]bool, target int) *Node {
-	values[0] = true
-	nodeMap := make(map[int]*Node)
-
-	for i := 0; i < target; i++ {
-		if values[i] {
-			node := createOrFetchNode(nodeMap, i)
-
-			for j := 1; j < 4; j++ {
-				if i+j > target {
-					break
-				}
-
-				if values[i+j] {
-					child := createOrFetchNode(nodeMap, i+j)
-					node.Children = append(node.Children, child)
-				}
-			}
-		}
-	}
-
-	return nodeMap[0]
-}
-
-func createOrFetchNode(nodeMap map[int]*Node, value int) *Node {
-	if node, ok := nodeMap[value]; ok {
-		return node
-	}
-
-	node := &Node{
-		Value:    value,
-		Children: make([]*Node, 0),
-	}
-	nodeMap[value] = node
-
-	return node
-}
-
-func countPaths(node *Node, target int) int {
-	if node.Value == target {
-		return 1
-	}
-
-	paths := 0
-	for _, child := range node.Children {
-		if child.Paths != 0 {
-			paths += child.Paths
-		} else {
-			paths += countPaths(child, target)
-		}
-	}
-	node.Paths = paths
-	return paths
-}
-
-func main() {
-	step := os.Args[1]
-	values := fileutils.InputParserIntMap(os.Args[2])
-
-	diffMap := make(map[int]int)
-
-	device := getMax(values) + 3
-	values[device] = true
-
-	switch step {
-	case "1":
-		diff := 0
-		for i := 0; i < device; i++ {
-			// increment diff, make sure we haven't broken the chain
-			// Note that we're actually logically checking the joltage at i+1
-			// but that serves us well here
-			diff++
-			if diff > 3 {
-				log.Panicf("Diff too big, bailing.")
-			}
-
-			// if we have a device at this joltage, register and reset count
-			if values[i+1] {
-				diffMap[diff]++
-				diff = 0
-			}
-		}
-		fmt.Println(diffMap[1] * diffMap[3])
-
-	case "2":
-		fmt.Println(findArrangements(values, device))
-	}
-}