The Euler function
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 5028 Accepted Submission(s): 2123
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
题意:求a到b之间的每个数的欧拉函数的和
#include<stdio.h> #include<string.h> #include<cstdio> #include<string> #include<math.h> #include<algorithm> #define LL long long #define PI atan(1.0)*4 #define DD double #define MAX 3000010 #define mod 100 #define dian 1.000000011 #define INF 0x3f3f3f using namespace std; LL s[MAX],a[MAX]; void el() { LL i,j; for(i=2;i<MAX;i++) { if(!a[i]) { for(j=i;j<MAX;j+=i) { if(!a[j]) a[j]=j; a[j]=a[j]/i*(i-1); } } a[i]+=a[i-1]; } } int main() { LL n,m,j,i,t; el(); while(scanf("%lld%lld",&n,&m)!=EOF) { t=a[m]-a[n-1]; printf("%lld ",t); } return 0; }