Weird copying linked list-ish thing with random

leetcode/stdlib.py

@@ -1,3 +1,4 @@
+import dataclasses
 import typing
 
 
@@ -14,6 +15,30 @@ class ListNode:
         self.next = next
 
 
+class ListNodeRandom:
+    """ListNodeRandom is another weirdo linked list thing from
+    leetcode that is obviously very different than a binary tree
+    node :upside_down_face:
+    """
+
+    def __init__(
+        self,
+        x: int,
+        next: typing.Optional["ListNodeRandom"] = None,
+        random: typing.Optional["ListNodeRandom"] = None,
+    ):
+        self.val = x
+        self.next = next
+        self.random = random
+
+
+@dataclasses.dataclass
+class ListNodeRandomNicely:
+    val: int
+    next: typing.Optional["ListNodeRandomNicely"] = None
+    random: typing.Optional["ListNodeRandomNicely"] = None
+
+
 class BinaryTreeNode(typing.Protocol):
     val: int
     left: typing.Optional["BinaryTreeNode"]

leetcode/stuff.py

@@ -509,3 +509,29 @@ def count_factorial_trailing_zeroes(number: int) -> int:
         divisor *= 5
 
     return zeroes_count
+
+
+def copy_random_list(
+    head: stdlib.ListNodeRandom | None,
+) -> stdlib.ListNodeRandom | None:
+    if head is None:
+        return None
+
+    ordered = []
+    cur = head
+    while cur is not None:
+        ordered.append(cur)
+        cur = cur.next
+
+    ordered_copy = [stdlib.ListNodeRandom(entry.val) for entry in ordered]
+
+    hash_idx = {hash(n): i for i, n in enumerate(ordered)}
+
+    for i, entry in enumerate(ordered):
+        if i + 1 < len(ordered_copy):
+            ordered_copy[i].next = ordered_copy[i + 1]
+
+        if entry.random is not None:
+            ordered_copy[i].random = ordered_copy[hash_idx[hash(entry.random)]]
+
+    return ordered_copy[0]