摘要：
链接： https://codeforces.com/contest/1251/problem/C 题意： You are given a huge integer a consisting of n digits (n is between 1 and 3⋅105, inclusive). It 阅读全文
摘要：
链接： https://codeforces.com/contest/1251/problem/B 题意： A palindrome is a string t which reads the same backward as forward (formally, t[i]=t[|t|+1−i] f 阅读全文
摘要：
链接： https://codeforces.com/contest/1251/problem/A 题意： Recently Polycarp noticed that some of the buttons of his keyboard are malfunctioning. For simpl 阅读全文