Solved: 322. Coin Change #40
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oda
reviewed
May 5, 2025
| if amount is None: | ||
| return -1 | ||
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| @lru_cache |
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これ、サイズいくつになってますか? (意図して書いたか確認したいという意図です。)
cache でもいいかもしれませんね。
特に問題ないかと思います。
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これ、サイズいくつになってますか? (意図して書いたか確認したいという意図です。)
指定していないので128になっていますね。サイズに制限をかけようという意図でlru_cacheを選びました。
が、よくよく考えるとamount分のサイズを確保しないといけないですし、サイズもそこまで大きくないのでcacheにするべきですね。
@functools.lru_cache(maxsize=128, typed=False)
https://docs.python.org/ja/3.13/library/functools.html#functools.lru_cache
Fuminiton
commented
May 6, 2025
| amount、numsが空の時、作れない時は-1を返す。 | ||
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| amount * len(coins) が時間計算量だが、10^4 * 12 ~ 10^5程度なので、現状は問題ない。 | ||
| 実際、このプログラムが使われるのは自動販売機のようなお釣りを出すシステムだと思うので、amountが10^6であったり、coinの種類が1000個になったりすることは考えにくいので、一旦、この実装で良いと思う。 |
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よくよく考えたら、コンビニのセルフレジシステムでも使える。が、円ならお釣りになるのは10^4未満のはずなのでほぼ問題の制約と一致している。
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322. Coin Change