可怜丶流年

摘要： Problem DescriptionFang Fang says she wants to be remembered.I promise her. We define the sequenceFof strings.F0=‘‘f",F1=‘‘ff",F2=‘‘cff",Fn=Fn−1+‘‘f",... 阅读全文

摘要： Problem DescriptionGiven the sequenceAwithnintegerst1,t2,⋯,tn. Given the integral coefficientsaandb. The fact that select two elementstiandtjofAandi≠j... 阅读全文