目录观点一（灵剑）1. 提前return2. 策略模式2.1 多态2.2 枚举3. 学会使用 Optional4. 数组小技巧观点二（IT技术控）观点一（灵剑）
Seems like this might be easy, but from reading other SO answers there are a number of ways for it to possibly work:
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