day_07.r

data <- readLines("data_07.txt")

files <- data.frame(id=1,parent=0,name="/",type="dir",size=0)

find_next <- function(x){
  while(x < length(data)){
    x=x+1
    if(strsplit(data[x]," ")[[1]][1]=="$" || x > length(data)){
      return(x)
    }
    
  }
  return(length(data)-1)
}

id = 1

for(line in 2:length(data)){
  this_line <- strsplit(data[line]," ")[[1]]
  this_command <- this_line[1]
  print(line)
  
  if(this_command=="$"){
    print("$ command")
    if(this_line[2]=="ls"){ # Listing
      print("..ls")
      line_seq = (line+1):(find_next(line)-1)
      for(i in line_seq){
        this_data <- strsplit(data[i]," ")[[1]]
        print(this_data)
        if(this_data[1] == "dir"){
          print("....dir")
          new_row <- data.frame(id=max(files$id)+1,
                                parent = id,
                                name = this_data[2],
                                type="dir",
                                size = 0)
          files <- rbind(files,new_row)
        }else{
          print("....file")
          new_row <- data.frame(id=max(files$id)+1,
                                parent = id,
                                name = this_data[2],
                                type="file",
                                size = this_data[1])
          files <- rbind(files,new_row)
        }
      }
      line = find_next(line)
      next
    }
    
    if(this_line[2]=="cd"){
      print("cd")
      if(this_line[3]==".."){
        print("....")
        tid <- id
        id <- subset(files,files$id==tid)$parent
      }else{
        print("forward")
        tid <- id
        id <- subset(files,files$name==this_line[3] & files$parent == tid)$id
      }
    }
    
  }
  
}

files <- subset(files,!name %in% c("ls","cd"))
files$size = as.numeric(files$size)

files <- files[order(-files$parent),]

for(i in 1:nrow(files)){
  this_row <- files[i,]
  if(this_row$type=="file"){
    this_parent = this_row$parent
    size = this_row$size
    while(this_parent != 1){
      files$size[files$id == this_parent]= files$size[files$id == this_parent ] + as.numeric(size)
      parent_row <- subset(files,files$id==this_parent)
      this_parent <- parent_row$parent
    }
    files$size[files$id==1]=files$size[files$id==1]+size
  }
}

fx <- subset(files,size <= 100000 & type=="dir")
print(sum(fx$size))

# part 2
used = subset(files,id==1)$size
total = 70000000
update = 30000000
difr = total-used
need = update - difr

fy = subset(files,type=="dir" & size >= need)
min(fy$size)