Keith_

摘要： #B. Quick Sort You are given a permutation【排列】† $p$ of length $n$ and a positive integer $k≤n$. In one operation, you: Choose $k$ distinct elements【不连 阅读全文

摘要： #A. Greatest Convex You are given an integer $k$. Find the largest integer $x$, where $1≤x<k$, such that $x!+(x−1)!$† is a multiple of ‡ $k$, or deter 阅读全文