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5474:A simple graph problem

题目描述
Suppose you have a graph with only n vertices and no edges. Now for every vertex you will select a vertex randomly and equiprobability, and then add an undirected edge between them (multiple edges and self-loop is allowed). At last you will have a graph with n vertices and n edges. So would you mind telling me what is the expected number of the cut vertices. (If you delete a cut vertex in a graph, the number of connected block in this graph will increase)
输入解释
The first line contains a number T, indicating the number of test cases.($1 \leq T \leq 50$)
For each case, there are only one number n ($1 \leq n \leq 10^5$), as described previously.
输出解释
For each case, first please output "Case #k: ", k is the number of test case. See sample output for more detail. And then, output the answer multiply $n^n$(mod $10^9 + 7$), to make sure the answer will always be an integer.
输入样例
3
1
2
3
输出样例
Case #1: 0
Case #2: 0
Case #3: 15
来自杭电HDUOJ的附加信息
Recommend hujie

该题目是Virtual Judge题目,来自 杭电HDUOJ

源链接: HDU-5474

最后修改于 2020-10-25T23:22:58+00:00 由爬虫自动更新

共提交 0

通过率 --%
时间上限 内存上限
2000/1000MS(Java/Others) 65536/65536K(Java/Others)