Day 7

1 files changed, 97 insertions, 0 deletions

diff --git a/day7/solution.nim b/day7/solution.nim
new file mode 100644
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+import std/strutils
+
+type
+  Command = string
+  # using LeFile for name because File already exists
+  LeFile = ref object
+    Size: int
+    Name: string
+
+type
+  Directory = ref object
+    Name: string
+    Files: seq[LeFile]
+    Parent: Directory
+    Subdirectories: seq[Directory]
+
+# Directory methods
+method cd(self: Directory, path: string): Directory =
+  if path == "..":
+    return self.Parent
+
+  for subdir in self.Subdirectories:
+    if subdir.Name == path:
+      return subdir
+
+method add(self: Directory, file: LeFile): void =
+  self.Files.add(file)
+
+method add(self: Directory, dir: Directory): void =
+  self.Subdirectories.add(dir)
+
+let total = 70_000_000 
+var part1 = 0
+var minRemoved = total
+
+method size(self: Directory, freeThreshold = total): int =
+  var size = 0
+  for file in self.Files:
+    size += file.Size
+
+  for subdir in self.Subdirectories:
+    size += subdir.size(freeThreshold)
+
+  if size <= 100_000:
+    part1 += size
+
+  if size >= freeThreshold:
+    minRemoved = min(minRemoved, size)
+
+  return size
+
+proc run(root: Directory, input: seq[Command]): void = 
+  # start pc from 1 to ignore "cd /" command thats coming first
+  var pc = 1
+  var current = root
+
+  let endpc = input.len()
+  while pc < endpc:
+    let command = input[pc]
+    assert(command[0] == '$')
+    
+    let tokens = command.splitWhitespace()
+
+    case tokens[1]:
+      of "cd":
+        current = current.cd(tokens[2])
+        pc += 1
+      of "ls":
+        pc += 1
+        while pc < endpc:
+          let file = input[pc]
+          # end of file list
+          if file[0] == '$':
+            break
+          
+          let fileInfo = file.splitWhitespace()
+          if fileInfo[0] == "dir":
+            current.add(Directory(Name: fileInfo[1], Files: @[], Parent: current, Subdirectories: @[]))
+          else:
+            current.add(LeFile(Size: fileInfo[0].parseInt(), Name: fileInfo[1]))
+          pc += 1
+      else:
+        assert(false)
+
+  return
+
+let content = readFile("./input.txt").strip().splitLines()
+
+var root = Directory(Name: "/", Files: @[], Parent: nil, Subdirectories: @[])
+run(root, content)
+
+let totalUsed = root.size()
+let totalFree = total - totalUsed
+discard root.size(30_000_000 - totalFree)
+
+echo part1
+echo minRemoved