摘要：
考试时候遇到这种题只会找规律 You've got an array a, consisting of n integers. The array elements are indexed from 1 to n. Let's determine a two step operation like 阅读全文
摘要：
通过霍尔定理转化判定方式的一步还是很妙的 The biggest gold mine in Berland consists of n caves, connected by n - 1 transitions. The entrance to the mine leads to the cave 阅读全文