2024 Dec 09th

Python/2024/09/main.py

@@ -0,0 +1,66 @@
+input = open("input", 'r').read().strip()
+
+# d = [int(line) for line in input]
+d = {id: int(line) for id, line in enumerate(input)}
+
+def entry(pos, id, length):
+    return {"pos": pos, "id": id, "length": length}
+pos = 0
+s = []
+e = []
+for id, leng in d.items():
+    if leng <= 0:
+        continue
+    if id % 2 == 0:
+        s.append(entry(pos, id // 2, leng))
+    else:
+        e.append(entry(pos, -1, leng))
+    pos += leng
+
+# print(d)
+
+def run():
+    start = 0
+    end = len(d) - 1
+    if end % 2 != 0:
+        end -= 1
+    pos = 0
+    checksum = 0
+
+    while start <= end:
+        if start % 2 == 0: # Full
+            checksum += pos * (start // 2)
+            pos += 1
+            d[start] -= 1
+            while d[start] == 0:
+                start += 1
+        else: # Empty
+            checksum += pos * (end // 2)
+            pos += 1
+            d[start] -= 1
+            while d[start] == 0:
+                start += 1
+            d[end] -= 1
+            while d[end] == 0:
+                end -= 2
+    return checksum
+
+def run2():
+    # a = s[-1]
+    # print(a)
+    for file in reversed(s):
+        for empty in e:
+            if empty['length'] >= file['length'] and file['pos'] > empty['pos']:
+                file['pos'] = empty['pos']
+                empty['pos'] += file['length']
+                empty['length'] = empty['length'] - file['length']
+                break
+
+    checksum = sum([
+        sum([(file['pos']+i) * file['id'] for i in range(file['length'])]) for file in s
+    ])
+    return checksum
+
+
+print(run())
+print(run2())