2024: Day 9 - part 1

Author: MiLk

2024/python/day9/__init__.py

@@ -0,0 +1,95 @@
+from math import floor
+from collections import OrderedDict
+
+
+from utils.file import read_input
+
+disk_map = list(map(int, read_input(__package__)[0]))
+
+def p1() -> int:
+    uncompressed_disk_map: list[str] = []
+    for i in range(floor((len(disk_map) + 1) / 2)):
+        occupied = disk_map[i * 2]
+        for _ in range(occupied):
+            uncompressed_disk_map.append(str(i))
+        try:
+            free = disk_map[i * 2 + 1]
+            for _ in range(free):
+                uncompressed_disk_map.append(".")
+        except IndexError:
+            pass
+
+    size = len(uncompressed_disk_map)
+    if size < 100:
+        print("".join(uncompressed_disk_map))
+
+
+    while True:
+        free_space = next(i for i in range(size) if uncompressed_disk_map[i] == ".")
+        last_character = next(size - i for i in range(1, size) if uncompressed_disk_map[size - i].isdigit())
+        if free_space > last_character:
+            break
+        uncompressed_disk_map[free_space], uncompressed_disk_map[last_character] = uncompressed_disk_map[last_character], uncompressed_disk_map[free_space]
+
+    return sum(
+        i * int(n)
+        for i, n in enumerate(uncompressed_disk_map)
+        if n != "."
+    )
+
+def p2() -> int:
+    files = OrderedDict({
+        i: disk_map[i * 2]
+        for i in range(floor((len(disk_map) + 1) / 2))
+    })
+
+    reordered: list[tuple[int, int]] = []
+    for i in range(floor((len(disk_map) + 1) / 2)):
+        try:
+            free = disk_map[i * 2 + 1]
+        except IndexError:
+            free = 0
+        if i in files.keys():
+            reordered.append((i, files[i]))
+            del files[i]
+            if not files:
+                break
+        else:
+            reordered.append((-1, disk_map[i * 2]))
+
+        while free > 0:
+            n = next((n_ for n_, size in reversed(files.items()) if size <= free), None)
+            if n is None:
+                break
+            consumed = files[n]
+            reordered.append((n, consumed))
+            free -= consumed
+            del files[n]
+
+            if not files:
+                break
+
+        if free > 0:
+            reordered.append((-1, free))
+
+    reordered_disk_map = ""
+    for idx, length in reordered:
+        if idx == -1:
+            reordered_disk_map += "." * length
+        else:
+            reordered_disk_map += str(idx) * length
+
+    if len(reordered_disk_map) < 100:
+        print(reordered_disk_map)
+    return sum(
+        i * int(n)
+        for i, n in enumerate(reordered_disk_map)
+        if n != "."
+    )
+
+
+#print("Part 1:", p1())
+
+# 84975570147 too low
+print("Part 2:", p2())
+