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hroc135
reviewed
Jun 23, 2025
| @@ -0,0 +1,14 @@ | |||
| class Solution: | |||
| def kthGrammar(self, n: int, k: int) -> int: | |||
| def kth_grammer_helper(n, k): | |||
nodchip
reviewed
Jun 24, 2025
| * recursion の問題だなーとは思いながら考えたけど明確な解法思いつかず。 | ||
| * とりあえず愚直な解法を実装してみたけど memory limit exceeded | ||
| * n が 30 までということは、2^30 文字の文字列を保存することになる。 | ||
| * `sys.getsizeof("a") -> 50` (bytes) とかなので、途方もないサイズになる |
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文字列本体のメモリ + Python のオブジェクトに必要なメモリ + str に必要なメモリで 50 バイトとなっているのだと思います。文字一文字あたりは 1 バイトのようです。
>>> import sys
>>> sys.getsizeof("a")
50
>>> sys.getsizeof("aa")
51
>>> sys.getsizeof("aaa")
52
>>> sys.getsizeof("aaaa")
53
| if n == 1: | ||
| return 0 | ||
|
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||
| if k % 2: |
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否定してから int にキャストしているのが、やや分かりずらく感じました。引き算のほうがシンプルだと思いました。
if k % 2:
return self.kthGrammar(n - 1, (k + 1) // 2)
else:
return 1 - self.kthGrammar(n - 1, (k + 1) // 2)
ryosuketc
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779. K-th Symbol in Grammar
https://leetcode.com/problems/k-th-symbol-in-grammar/