再用n2的时间（两重循环）枚举d-c，并将b-c的值作为键，在Hash数组中查找是否存在。如果能找到crucial相同的node点，则找到了一组满足 d-c = a+b的值。（注意检查a b c d 四个数不重复） Reside plants are more than simply decorative elements inside of a freshwater aquarium. They add to oxygenation, enable retain h2o good quality, and provide organic habitats for fish. 一個月 查看 時間: 全部時間 Ti... https://pearlaquatics.my/5-quick-hacks-of-professional-pond-cleaning/