Add solution for day 7

.gitignore

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+*.swp

python/day07.py

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+#!/usr/bin/env python3
+
+from dataclasses import dataclass, field
+from sys import maxsize
+from util import read_input
+
+
+@dataclass
+class File:
+    name: str
+    size: int
+
+    def __hash__(self):
+        return hash('file' + self.name)
+
+
+@dataclass
+class Directory:
+    name: str
+    children: set = field(default_factory=set)
+
+    def __hash__(self):
+        return hash('dir' + self.name)
+
+
+def build_dir_tree(commands):
+    root = Directory('/')
+    current_path = [root]
+
+    for line in commands:
+        if line.startswith("$"):
+            command = line.split(' ')
+            if command[1] == 'cd':
+                name = command[2].strip()
+                if name == '/':
+                    current_path = [root]
+                elif name == '..':
+                    if len(current_path) > 0:
+                        current_path.pop()
+                else:
+                    for child in current_path[-1].children:
+                        if child.name == name:
+                            current_path.append(child)
+                            break
+            elif command[1] == 'ls':
+                pass
+        elif line.startswith("dir"):
+            name = line.split(' ')[1].strip()
+            current_path[-1].children.add(Directory(name))
+        elif line[0].isdigit():
+            size, name = line.split(' ')
+            name = name.strip()
+            size = int(size)
+            parent = current_path[-1]
+            parent.children.add(File(name, size))
+    return root
+
+
+def sum_dir(directory, total):
+    dir_sum = 0
+    child_sum = 0
+    for child in directory.children:
+        if isinstance(child, Directory):
+            child_sum += sum_dir(child, total)
+        elif isinstance(child, File):
+            dir_sum += child.size
+    if dir_sum + child_sum < 100000:
+        total[0] += dir_sum + child_sum
+    return dir_sum + child_sum
+
+
+def closest_dir(directory, space_needed, smallest_deletion):
+    total = 0
+    for child in directory.children:
+        if isinstance(child, Directory):
+            total += closest_dir(child, space_needed, smallest_deletion)
+        elif isinstance(child, File):
+            total += child.size
+    if total >= space_needed:
+        if total < smallest_deletion[0]:
+            smallest_deletion[0] = total
+    return total
+
+
+def part1(commands):
+    root = build_dir_tree(commands)
+    total = [0]
+    sum_dir(root, total)
+    return total[0]
+
+
+def part2(commands):
+    root = build_dir_tree(commands)
+    root_size = sum_dir(root, [0])
+    space_used = 70000000 - root_size
+    space_needed = 30000000 - space_used
+    smallest_deletion = [maxsize]
+    closest_dir(root, space_needed, smallest_deletion)
+    return smallest_deletion[0]
+
+
+test_input = read_input("Day07_test")
+assert 95437 == part1(test_input)
+
+real_input = read_input('Day07')
+print(part1(real_input))
+
+assert 24933642 == part2(test_input)
+print(part2(real_input))