[hdu 5672][BestCoder Round #81 t3] String 尺取法||双指针法
StringAccepts:84Submissions:373TimeLimit:2000/1000MS(Java/Others)MemoryLimit:65536/65536K(Java/Others)问题描述有一个10≤10\leq10≤长度≤1,000,000\leq1,000,000≤1,000,000的字符串,仅由小写字母构成。求有多少个子串,包含有至少k(1≤k≤26)k(1\