标签：
The Euler function
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 4548 Accepted Submission(s): 1895
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)
Input
There are several test cases. Each line has two integers a, b (2<a<b<3000000).
Output
Output the result of (a)+ (a+1)+....+ (b)
Sample Input
Sample Output
代码：
#include<stdio.h>
#define MAX 3000010
long long euler[MAX];
int init()
{
int i,j;
for(i=2;i<MAX;i++)
{
if(!euler[i])
{
for(j=i;j<MAX;j+=i)
{
if(!euler[j])
euler[j]=j;
euler[j]=euler[j]/i*(i-1);
}
}
euler[i]+=euler[i-1];
}
}
int main()
{
int a,b;
init();
while(scanf("%d%d",&a,&b)!=EOF)
{
printf("%lld\n",euler[b]-euler[a-1]);
}
return 0;
}
版权声明：本文为博主原创文章，未经博主允许不得转载。
hdoj 2824 The Euler function
标签：
原文地址：http://blog.csdn.net/longge33445/article/details/47984105
