A. Boring Apartments(思维)
B. Yet Another Bookshelf(思维)
C. Dominant Piranha(思维)
D. Districts Connection(思维+构造)
E. Two Round Dances(思维+圆排列组合数学)
F. Zero Remainder Sum(思维+四维dp）
G. Reducing Delivery Cost(思维+最短路)
