2018.9 ECNU ICPC/CCPC Trial Round #2

N. Nale Sort O. Oxx Playing Pokemon Go P. Prefix Free Code Q. Query On Tree R. Rabbit's Howse S. Substring Diff T. Transform IP Database U. Ultmaster Dividing The Cake V. Viva La Vida W. Weight Of Subsequence X. X Window Y. You Only Live Once Z. Zerol And KBlack