🌅

solutions/day7/day7.go

@@ -0,0 +1,159 @@
+package day7
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+type FileSystem struct {
+	name           string
+	parent         *FileSystem
+	subdirectories []*FileSystem
+	files          []FileInfo
+}
+
+func newFileSystem(name string, parent *FileSystem) *FileSystem {
+	return &FileSystem{name, parent, []*FileSystem{}, []FileInfo{}}
+}
+
+func printFileTree(tree *FileSystem, prefix string) {
+	fmt.Println(prefix, "-", tree.name, fmt.Sprintf("(dir size=%d)", totalSize(tree)))
+
+	for _, file := range tree.files {
+		fmt.Println(prefix, " ", "-", file.name, fmt.Sprintf("(file, size=%d)", file.size))
+	}
+
+	for _, dir := range tree.subdirectories {
+		printFileTree(dir, prefix+"  ")
+	}
+}
+
+func totalSize(tree *FileSystem) int {
+	total := 0
+
+	for _, file := range tree.files {
+		total += file.size
+	}
+
+	for _, dir := range tree.subdirectories {
+		total += totalSize(dir)
+	}
+
+	return total
+}
+
+func computePart1(tree *FileSystem) int {
+	result := 0
+
+	for _, dir := range tree.subdirectories {
+		result += computePart1(dir)
+	}
+
+	currentSize := totalSize(tree)
+	if currentSize <= 100000 {
+		result += currentSize
+	}
+
+	return result
+}
+
+func computePart2(tree *FileSystem, size int) int {
+	result := 70000000
+
+	for _, dir := range tree.subdirectories {
+		subResult := computePart2(dir, size)
+		if subResult < result {
+			result = subResult
+		}
+	}
+
+	currentSize := totalSize(tree)
+	if currentSize > size && currentSize < result {
+		result = currentSize
+	}
+
+	return result
+}
+
+type FileInfo struct {
+	name string
+	size int
+}
+
+func parseFileInfo(line string) (result FileInfo, err error) {
+	splits := strings.Split(line, " ")
+	if len(splits) != 2 {
+		err = errors.New("too many values from file info split")
+		return
+	}
+
+	size, err := strconv.Atoi(splits[0])
+	if err != nil {
+		err = errors.New(fmt.Sprintf("could not parse file size: '%s'", splits[0]))
+		return
+	}
+
+	result = FileInfo{splits[1], size}
+	return
+}
+
+func Run(filename string) {
+	file, err := os.Open(filename)
+	if err != nil {
+		fmt.Println("Error opening file:", err)
+		return
+	}
+
+	scanner := bufio.NewScanner(file)
+	scanner.Split(bufio.ScanLines)
+
+	root := newFileSystem("/", nil)
+	current := root
+
+	for scanner.Scan() {
+		line := scanner.Text()
+
+		fmt.Println("line", line)
+		if strings.HasPrefix(line, "$ cd /") {
+			current = root
+		} else if strings.HasPrefix(line, "$ cd ..") {
+			current = current.parent
+		} else if strings.HasPrefix(line, "$ cd ") {
+			for _, subdir := range current.subdirectories {
+				if subdir.name == line[5:] {
+					current = subdir
+					continue
+				}
+			}
+		} else if strings.HasPrefix(line, "$ ls") {
+			// don't do anything
+		} else if strings.HasPrefix(line, "dir ") {
+			newTree := newFileSystem(line[4:], current)
+			current.subdirectories = append(current.subdirectories, newTree)
+		} else {
+			fileInfo, err := parseFileInfo(line)
+			if err != nil {
+				fmt.Println("PANIC:", err)
+				return
+			}
+
+			current.files = append((*current).files, fileInfo)
+		}
+	}
+
+	file.Close()
+
+	printFileTree(root, "")
+	fmt.Println("example first part", computePart1(root))
+
+	unusedSpace := 70000000 - totalSize(root)
+	fmt.Println("unused space is currently", unusedSpace)
+	needToGet := 30000000 - unusedSpace
+	fmt.Println("need to find a directory at least", needToGet, "bytes big")
+	fmt.Println("that directory has size", computePart2(root, needToGet))
+
+}