Implement alternative solution for d9

2024/d9.py

@@ -1,8 +1,4 @@
 from lib import get_data
-from lib import Grid2D
-from lib import ints
-from itertools import combinations
-from collections import defaultdict
 from copy import deepcopy
 
 data = get_data(__file__)

2024/d9_2.py

@@ -0,0 +1,81 @@
+from lib import get_data
+
+data = get_data("d9.py")
+
+
+def parse(data):
+    xs = []
+    f = True
+    i = 0
+    for c in data.strip():
+        if f:
+            for _ in range(int(c)):
+                xs.append(i)
+            f = False
+            i += 1
+        else:
+            for _ in range(int(c)):
+                xs.append(".")
+            f = True
+    return xs
+
+
+def score(xs):
+    t = 0
+    for i, j in enumerate(xs):
+        if j == ".":
+            continue
+        t += i * j
+    return t
+
+
+xs = parse(data)
+i, j = 0, len(xs) - 1
+while i <= j:
+    while xs[i] != ".":
+        i += 1
+
+    while xs[j] == ".":
+        j -= 1
+
+    if not i <= j:
+        break
+
+    xs[i], xs[j] = xs[j], xs[i]
+
+print(score(xs))
+xs = parse(data)
+
+idx = {}
+ids = []
+for i, x in enumerate(xs):
+    if x == ".":
+        continue
+    if not x in idx:
+        idx[x] = i
+        ids.append(x)
+
+while ids:
+    id = ids.pop()
+    i1, i2 = idx[id], idx[id]
+    while i2 < len(xs) and xs[i2] == id:
+        i2 += 1
+
+    j1 = 0
+    while j1 < i1:
+        while xs[j1] != ".":
+            j1 += 1
+        if not j1 < i1:
+            break
+        j2 = j1
+        while xs[j2] == ".":
+            j2 += 1
+        assert j2 <= i1
+
+        if i2 - i1 <= j2 - j1:
+            for j, i in zip(range(j1, j2), range(i1, i2)):
+                xs[j], xs[i] = xs[i], xs[j]
+            break
+        j1 = j2
+
+print(score(xs))