晴天要下雨

摘要： Period Time Limit: 3000MS Memory Limit: 30000K Total Submissions: 22012 Accepted: 10679 Description For each prefix of a given string S with N charact 阅读全文

摘要： Time Limit: 3000MS Memory Limit: 65536K Total Submissions: 65854 Accepted: 27197 Description Given two strings a and b we define a*b to be their conca 阅读全文