The Euler function |
| Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others) |
| Total Submission(s): 134 Accepted Submission(s): 76 |
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Problem Description
The Euler function phi is an important kind of function in number
theory, (n) represents the amount of the numbers which are smaller
than n and coprime to n, and this function has a lot of beautiful
characteristics. Here comes a very easy question: suppose you are given
a, b, try to calculate (a)+ (a+1)+....+ (b)
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Input
There are several test cases. Each line has two integers a, b (2<a<b<3000000).
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Output
Output the result of (a)+ (a+1)+....+ (b) |
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Sample Input
3 100 |
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Sample Output
3042 |
计算欧拉函数
可以像计算质数那样子
记住两个重要的结论 (p为质数 x % p==0 &&x/p % p ==0)E(x*p)=E(x)*p
(p为质数 x % p==0 && x/p % p !=0)E(x*p)=E(x)*(p-1)
http://www.cppblog.com/RyanWang/archive/2009/07/19/90512.aspx?opt=admin（很好）
http://qianmacao.blog.163.com/blog/static/203397180201231625353697/（没看懂）