1 files changed, 53 insertions, 0 deletions
diff --git a/2023/15/solve.py b/2023/15/solve.py
new file mode 100644
index 0000000..00d86d9
--- /dev/null
+++ b/2023/15/solve.py
@@ -0,0 +1,53 @@
+L = open("input").read().strip().split(",")
+
+
+def hash(s):
+    current = 0
+    for c in s:
+        current += ord(c)
+        current *= 17
+        current %= 256
+    return current
+
+
+def solve1():
+    res = 0
+    for l in L:
+        res += hash(l)
+    print(res)
+
+
+def solve2():
+    res = 0
+
+    boxes = dict()  # defaultdict would be cheating!!1!!!1!
+    for l in L:
+        if l[-1] == "-":
+            label = l[:-1]
+            box = hash(label)
+            boxes[box] = [
+                (lab, foc) for (lab, foc) in boxes.get(box, []) if lab != label
+            ]
+        elif l[-2] == "=":
+            label = l[:-2]
+            focal = int(l[-1])
+            box = hash(label)
+            labels = [lab for (lab, foc) in boxes.get(box, [])]
+            if label in labels:
+                boxes[box] = [
+                    (lab, focal if label == lab else foc)
+                    for (lab, foc) in boxes[box]
+                ]
+            else:
+                if box not in boxes:
+                    boxes[box] = []
+                boxes[box].append((label, focal))
+
+    for i, stacked in boxes.items():
+        for j, box in enumerate(stacked):
+            res += (i + 1) * (j + 1) * box[1]
+    print(res)
+
+
+solve1()
+solve2()