Day7 solutions

day7/day7.go

@@ -0,0 +1,104 @@
+package day7
+
+import (
+	"strconv"
+	"strings"
+)
+
+func Day7Logic() (int64, int64) {
+	input := strings.Split(input7, "\n")
+	root := buildFileSystem(input)
+
+	unusedDiskSpace := part2TotalDiskSpace - root.Size
+	spaceToFreeUp := part2SpaceNeeded - unusedDiskSpace
+
+	part1, part2 := day7Logic(&root, spaceToFreeUp, root.Size)
+
+	return part1, part2
+}
+
+type directory struct {
+	Name        string
+	Directories []*directory
+	Files       []file
+	Parent      *directory
+	Size        int64
+}
+
+type file struct {
+	Name string
+	Size int64
+}
+
+const part1DirMaxLimit = 100000
+const part2TotalDiskSpace = 70000000
+const part2SpaceNeeded = 30000000
+
+func day7Logic(dir *directory, spaceNeeded int64, spaceToDelete int64) (int64, int64) {
+
+	var part1 int64
+	var part2 = spaceToDelete
+
+	if dir.Size <= part1DirMaxLimit {
+		part1 += dir.Size
+	}
+
+	if dir.Size >= spaceNeeded && dir.Size < part2 {
+		part2 = dir.Size
+	}
+
+	for _, d := range dir.Directories {
+		temp1, temp2 := day7Logic(d, spaceNeeded, part2)
+
+		part1 += temp1
+		part2 = temp2
+	}
+
+	return part1, part2
+}
+
+func buildFileSystem(commands []string) directory {
+	var root directory
+	var currentDir = &root
+
+	for _, command := range commands {
+		cmd := strings.Split(command, " ")
+		if strings.HasPrefix(command, "$") {
+			// if here, means input is a command
+			switch cmd[1] {
+			case "cd":
+				if cmd[2] == ".." {
+					currentDir = currentDir.Parent
+				} else {
+					for _, dir := range currentDir.Directories {
+						if dir.Name == cmd[2] {
+							currentDir = dir
+						}
+					}
+				}
+			case "ls":
+			}
+		} else {
+			// if here, means input is a file or directory
+			switch cmd[0] {
+			case "dir":
+				dir := directory{Name: cmd[1], Parent: currentDir}
+				currentDir.Directories = append(currentDir.Directories, &dir)
+			default:
+				size, _ := strconv.ParseInt(cmd[0], 10, 64)
+				newFile := file{Name: cmd[1], Size: size}
+
+				currentDir.Files = append(currentDir.Files, newFile)
+				increaseDirSize(size, currentDir)
+			}
+		}
+	}
+	return root
+}
+
+func increaseDirSize(size int64, dir *directory) {
+	dir.Size += size
+	if dir.Parent != nil {
+		increaseDirSize(size, dir.Parent)
+	}
+}