python/TangDou/AcWing/RongChi/HDU2204_2.cpp

#include <bits/stdc++.h>
using namespace std;
#define LL long long
const int N = 100 + 100;

// 筛法求莫比乌斯函数
LL mu[N], sum[N];
int primes[N], cnt;
bool st[N];
void get_mobius(LL n) {
    mu[1] = 1;
    for (LL i = 2; i <= n; i++) {
        if (!st[i]) {
            primes[cnt++] = i;
            mu[i] = -1;
        }
        for (LL j = 0; primes[j] <= n / i; j++) {
            LL t = primes[j] * i;
            st[t] = true;
            if (i % primes[j] == 0) {
                mu[t] = 0;
                break;
            }
            mu[t] = mu[i] * -1;
        }
    }
    // 维护u(x)前缀和
    // 这玩意有啥用？
    for (LL i = 1; i <= n; i++) sum[i] = sum[i - 1] + mu[i];
}

int main() {
    // 筛法求莫比乌斯函数
    get_mobius(N - 1);

    LL T;
    while (cin >> T) {
        LL s = 1;
        for (LL i = 2; i <= 64; i++) s -= mu[i] * (LL)(pow(T * 1.0, 1.0 / i) - 1);
        cout << s << endl;
    }
    return 0;
}