loj6221. 幂数！

题意

求出\(N(N \leq {10}^ {11})\)以内的幂数的个数及和。
幂数满足其所有质因数都至少有两个。

题解

不说了，又斯波了。
两个性质：
1.答案较小
2.幂数一定是\(a ^ 2 b ^ 3\)的形式

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 1e6 + 1;
ll n, ans1, ans2, a[N], b[N];
vector <ll> c;
bool sqrfree (ll x) {
    ll s = sqrtl(x + 0.5);
    return s * s != x;
}
int main () {
    cin >> n;
    a[0] = a[1] = 1;
    for (int i = 2; 1ll * i * i <= n; ++i) {
        a[++a[0]] = 1ll * i * i;
    }
    b[0] = b[1] = 1;
    for (int i = 2; 1ll * i * i * i <= n; ++i) {
        if (sqrfree(1ll * i * i * i)) {
            b[++b[0]] = 1ll * i * i * i;
        }
    }
    for (int i = 1; i <= a[0]; ++i) {
        for (int j = 1; j <= b[0] && a[i] * b[j] <= n; ++j) {
            c.emplace_back(a[i] * b[j]);
        }
    }
    sort(c.begin(), c.end());
    n = unique(c.begin(), c.end()) - c.begin();
    for (int i = 0; i < n; ++i) {
        ++ans1;
        ans2 += c[i];
    }
    cout << ans1 << endl;
    cout << ans2 << endl;
    return 0;
}