hrbeu 1347 Euler 欧拉值

#include<stdio.h>
#include<string.h>
#include<math.h>
#define LL long long
#define nmax  3000001
int prime[nmax], phi[nmax];
int plen;
void init() {
        int i, j;
        memset(phi, 0, sizeof(phi));
        for (i = 2, plen = 0; i < nmax; i++) {
                if (!phi[i]) {
                        phi[i] = i - 1;
                        prime[plen++] = i;
                }
                for (j = 0; (j < plen) && (i * prime[j] < nmax); j++) {
                        if (i % prime[j] == 0) {
                                phi[i * prime[j]] = phi[i] * prime[j];
                                break;
                        } else {
                                phi[i * prime[j]] = phi[i] * (prime[j] - 1);
                        }
                }
        }
}
int main() {
#ifndef ONLINE_JUDGE
        freopen("data.in", "r", stdin);
#endif
        int a, b, i;
        LL phiSum;
        init();
        while (~scanf("%d %d", &a, &b)) {
                for (i = a, phiSum = 0; i <= b; i++) {
                        phiSum += phi[i];
                }
                printf("%lld\n", phiSum);
        }
        return 0;
}