hdu2824The Euler function（打表）

The Euler function

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 5917    Accepted Submission(s): 2498

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

3 100

 

Sample Output

3042
#include<stdio.h>#include<string.h>#define LL long longLL p[3000010];void get(){memset(p,0,sizeof(p));for(int i=2;i<3000010;i++){if(!p[i])for(int j=i;j<3000010;j+=i){if(!p[j])p[j]=j;p[j]=p[j]*(i-1)/i;}}for(int i=3;i<3000010;i++)p[i]+=p[i-1];}int main(){int a,b;get();//printf("%lld\n",p[3]);while(~scanf("%d%d",&a,&b)){printf("%lld\n",p[b]-p[a-1]);}return 0;}