摘要：
You are given a prime number pp, nn integers a1,a2,…,ana1,a2,…,an, and an integer kk. Find the number of pairs of indexes (i,j)(i,j) (1≤i<j≤n1≤i<j≤n) 阅读全文
摘要：
Note that this is the first problem of the two similar problems. You can hack this problem only if you solve both problems. You are given a tree with 阅读全文