Add day 7 solutions

day7.cr

@@ -0,0 +1,64 @@
+require "advent"
+INPUT = input(2022, 7).lines[1..]
+
+class DirTree
+  property name : String
+  property files : Hash(String, Int64)
+  property subDirs : Array(DirTree)
+  property parent : DirTree?
+
+  def initialize(@name, @parent)
+    @files = {} of String => Int64
+    @subDirs= [] of DirTree
+    @parent.try &.subDirs.<<(self)
+  end
+
+  def sum_yielding(&block : Int32 ->): Int32
+    size = 0
+    size += @subDirs.sum do |x|
+      x.sum_yielding(&block)
+    end
+    size += @files.sum { |k,v| v }
+    yield size
+    return size
+  end
+end
+
+dir = DirTree.new("", nil)
+
+INPUT.each do |line|
+  if line =~ /\$ cd (.+)$/
+    if $1 == ".."
+      dir = dir.parent.not_nil!
+    else
+      dir = DirTree.new($1, dir)
+    end
+  elsif line == "$ ls"
+  else
+    x, y = line.split(" ")
+    if x == "dir"
+    else
+      dir.files[y] = x.to_i64
+    end
+  end
+end
+
+while par = dir.parent
+  dir = par
+end
+
+total = 0
+outer_size = dir.sum_yielding do |i|
+  total += i if i <= 100000
+end
+puts total
+
+puts "Used: #{outer_size}"
+puts "Unused: #{70000000 -  outer_size}"
+to_delete = 30000000 - (70000000 - outer_size)
+puts "To delete: #{to_delete}"
+big_enough = [] of Int32
+outer_size = dir.sum_yielding do |i|
+  big_enough << i if i >= to_delete
+end
+puts big_enough.min