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6574:Rng

题目描述
Avin is studying how to synthesize data. Given an integer n, he constructs an interval using the following method: he first generates a integer r between 1 and n (both inclusive) uniform-randomly, and then generates another integer l between 1 and r (both inclusive) uniform-randomly. The interval [l, r] is then constructed. Avin has constructed two intervals using the method above. He asks you what the probability that two intervals intersect is. You should print p* ${q^{(-1)}}$(MOD 1, 000, 000, 007), while $\frac{p}{q}$ denoting the probability.
输入解释
Just one line contains the number n (1 ≤ n ≤ 1, 000, 000).
输出解释
Print the answer.
输入样例
1
2
输出样例
1
750000006
来自杭电HDUOJ的附加信息
Recommend liuyiding

该题目是Virtual Judge题目,来自 杭电HDUOJ

源链接: HDU-6574

最后修改于 2020-10-25T23:32:27+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) 262144/262144K(Java/Others)