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
#include<stdio.h>#define MAX_N 3000100int phi[MAX_N];void init(){ for(int i=1;i<MAX_N;i++) phi[i]=i; for(int i=2;i<MAX_N;i++) if(phi[i]==i) for(int j=i;j<MAX_N;j+=i) phi[j]=phi[j]/i*(i-1);}int main(){ init();int a,b; while(~scanf("%d%d",&a,&b)){ long long ans=0; for(int i=a;i<=b;i++) ans+=phi[i]; printf("%lld/n",ans); } return 0;}新闻热点
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