121. Best Time to Buy and Sell Stock #32
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potrue
reviewed
Sep 26, 2025
| # @return {Integer} | ||
| def max_profit(prices) | ||
| prices_size = prices.size | ||
| return 0 if prices_size <= 1 |
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試せていないので間違っていたら申し訳ないのですが、この行はなくても良い気がしました。
.each doの部分が回らずにそのまま0が出力されるのではないでしょうか。
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コメントありがとうございます！
おっしゃる通りなくても良いのですがサイズが1以下の時の処理をわかりやすくするために残していました。
| end | ||
| max_profit | ||
| end | ||
| ``` |
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price[i] が min_price より小さい場合は max_profit の更新はないため、min_price を更新して次のループに進むのもよさそうかなと思いました。
def max_profit(prices)
prices_size = prices.size
return 0 if prices_size <= 1
min_price = prices.first
max_profit = 0
(1...prices_size).each do |i|
if prices[i] < min_price
min_price = prices[i]
next
end
max_profit = [max_profit, prices[i] - min_price].max
end
max_profit
end
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コメントありがとうございます！
確かにそっちの方が意味がわかりやすいです。
どんな時でもmax_profitの更新をする必要はありませんね。
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解いた問題
121. Best Time to Buy and Sell Stock
使用言語
Ruby
次に解く問題
122. Best Time to Buy and Sell Stock II